Wikipedia:Manual of Style/Dates and numbers

Wikipedia project page

This page guides the presentation of numbers, dates, times, measurements, currencies, coordinates, and similar items in articles. The aim is to promote clarity, cohesion, and consistency, and to make the encyclopedia easier and more intuitive to use. For numbers, dates, and similar items in Wikipedia article titles, see the "Naming conventions (numbers and dates)" guideline.

Where this manual gives options, maintain consistency within an article unless there is a good reason to do otherwise. The Arbitration Committee has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style; edit-warring over optional styles is unacceptable.^[a] If discussion fails to resolve the question of which style to use in an article, defer to the style used by the first major contributor.

General notes

Quotations, titles, etc.

Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they use formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via [bracketed interpolation], article text, or footnotes.

Non-breaking spaces

Guidance on the use of non-breaking spaces ("hard spaces") is given in some sections below, but not all situations in which hard spaces ({{nbsp}} or  ) or {{nowrap}} may be appropriate are described. For further information see Wikipedia:Manual of Style § Non-breaking spaces and Wikipedia:Line-break handling.

Chronological items

Statements likely to become outdated

Shortcuts

• MOS:SINCE
• MOS:DATED
• MOS:CURRENT
• MOS:RECENT
• MOS:NOW

Except on pages that are inherently time-sensitive and updated regularly (e.g. the "Current events" portal), terms such as now, today, currently, present, to date, so far, soon, upcoming, ongoing, and recently should usually be avoided in favor of phrases such as during the 2010s, since 2010, and in August 2020. Wording can usually be modified to remove the "now" perspective: not she is the current director but she became director on 1 January 2024; not 2010–present but beginning in 2010 or since 2010. Terms likely to go out of date include best known for, holds the record for, etc.^[b] For current and future events, use phrases such as as of July 2024 or since the beginning of 2024 to signal the time-dependence of the information; use the template {{as of}} (or {{updated}}) in conjunction. Relative-time expressions are acceptable for very long periods, such as geological epochs: Humans diverged from other primates long ago, but only recently developed state legislatures.

Dates, months, and years

Shortcuts

• MOS:DATE
• MOS:DATEFORMAT
• MOS:YEAR

• These requirements do not apply to dates in quotations or titles; see Wikipedia:Manual of Style § Quotations.
• Special rules apply to citations; see Wikipedia:Citing sources § Citation style.
• See also Wikipedia:Overview of date formatting guidelines.

Formats

Shortcut

• MOS:UNLINKDATES

• Dates, years, and other chronological items should be linked only when they are relevant to the subject and likely to be useful to a reader; this rule does not apply to articles that are explicitly on a chronological item, e.g. 2002, 19th century (as discussed at Wikipedia:Linking § Chronological items).^[e]
• For issues related to dates in sortable tables, see Help:Sortable tables § Configuring the sorting and Help:Sortable tables § Date sorting problems, or consider using {{dts|Nov 1, 2008}}.
• Phrases such as Fourth of July (or July Fourth, but not July 4th), Cinco de Mayo, Seventh of March Speech, and Sete de Setembro are proper names, to which rules for dates do not apply (A typical Fourth of July celebration includes fireworks).

Shortcuts

• MOS:DATESNO
• MOS:BADDATE

Consistency

Shortcut

• MOS:DATEUNIFY

• Dates in article body text^[h] should all use the same format: She fell ill on 25 June 2005 and died on 28 June, not She fell ill on 25 June 2005 and died on June 28.
• Publication dates in an article's citations should all use the same format, which may be:
  • the format used in the article body text,
  • an abbreviated format from the "Acceptable date formats" table, provided the day and month elements are in the same order as in dates in the article body
  • the format expected in the citation style being used (but all-numeric date formats other than yyyy-mm-dd must still be avoided).
  For example, publication dates within a single article might be in one, but only one, of these formats (among others):
  • Jones, J. (20 September 2008)
  • Jones, J. (September 20, 2008)
  If an article uses a template such as {{Use mdy dates}} or {{Use dmy dates}}, then Citation Style 1 and 2 templates automatically render dates (|date=, |access-date=, |archive-date=, etc) in the specified format, regardless of the format they are entered in. (The |cs1-dates= parameter can be used to fine-tune the generated output, see Template:Use mdy dates § Auto-formatting citation template dates.)
• Access and archive dates in an article's citations should all use the same format, which may be:
  • the format used for publication dates in the article (see above);
  • the format expected in the citation style adopted in the article; or
  • yyyy-mm-dd
  For example, access/archive dates within a single article might be in one, but only one, of these formats (among others):
  • Jones, J. (September 20, 2008) ... Retrieved February 5, 2009.
  • Jones, J. (20 Sep 2008) ... Retrieved 5 Feb 2009.
  • Jones, J. (20 September 2008) ... Retrieved 2009-02-05.
  When a citation style does not expect differing date formats, it is permissible to normalize publication dates to the article body text date format, and/or access/archive dates to either, with date consistency being preferred.

Strong national ties to a topic

Shortcut

• MOS:DATETIES

For any given article, the choice of date format and the choice of national variety of English (see Wikipedia:Manual of Style § Strong national ties to a topic) are independent issues.

• Articles on topics with strong ties to a particular English-speaking country should generally use the date format most commonly used in that nation. For the United States this is (for example) July 4, 1976; for most other English-speaking countries it is 4 July 1976.
• Articles related to Canada may use either format with (as always) consistency within each article. (see Retaining existing format)
• Shortcut

  • MOS:MILFORMAT
  In topics where a date format that differs from the usual national one is in customary usage, that format should be used for related articles: for example, articles on the modern US military, including biographical articles related to the modern US military, should use day-before-month, in accordance with US military usage.

Retaining existing format

Shortcuts

• MOS:DATERET
• MOS:DATEVAR

• If an article has evolved using predominantly one date format, this format should be used throughout the article, unless there are reasons for changing it based on the topic's strong ties to a particular English-speaking country, or consensus on the article's talk page.
• The date format chosen in the first major contribution in the early stages of an article (i.e., the first non-stub version) should continue to be used, unless there is reason to change it based on the topic's strong ties to a particular English-speaking country, or consensus on the article's talk page.
• Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".

Era style

Shortcuts

• MOS:ERA
• MOS:BCE

• The default calendar eras are Anno Domini (BC and AD) and Common Era (BCE and CE). Either convention may be appropriate for use in Wikipedia articles depending on the article context. Apply Wikipedia:Manual of Style § Retaining existing styles with regard to changes from one era to the other.
  • Use either the BC–AD or the BCE–CE notation consistently within the same article. Exception: do not change direct quotations, titles, etc.
  • An article's established era style should not be changed without reasons specific to its content; seek consensus on the talk page first (applying Wikipedia:Manual of Style § Retaining existing styles) by opening a discussion under a heading using the word era, or another similarly expressive heading, and briefly stating why the style should be changed.
  • BCE and CE or BC and AD are written in upper case, unspaced, without a full stop (period), and separated from the numeric year by a space (5 BC, not 5BC). It is advisable to use a non-breaking space.
  • AD appears before or after a year (AD 106, 106 AD); BCE, CE, and BC always appear after (106 CE, 3700 BCE, 3700 BC).
  • In general, omit CE or AD, except to avoid ambiguity or awkwardness.
    • Typically, write The Norman Conquest took place in 1066 not 1066 CE or AD 1066.
    • But Plotinus lived at the end of the 3rd century AD (not simply at the end of the 3rd century) may avoid confusion unless the era is clear from context.
    • One- and two-digit years may look more natural with an era marker (born in 2 AD or born January 15, 22 CE, not born in 2 nor January 15, 22).
    • Ranges beginning in BC / BCE should specify the ending era: write 450 to 200 BCE or 450 BC to 200 BC or 450 BCE to 200 CE, but not 450 BCE to 200. (see Ranges)
• Uncalibrated (BCE) radiocarbon dates: Calibrated and uncalibrated dates can diverge widely, and some sources distinguish the two only via BCE or BC (for calibrated dates) versus bce or bc (uncalibrated). When feasible, avoid uncalibrated dates except in direct quotations, and even then ideally give the calibrated date in a footnote or square-bracketed note – [3250 BCE calibrated], or at least indicate the date type – [uncalibrated]. This also applies to other dating systems in which a calibration distinction is drawn.
• BP or YBP: In scientific and academic contexts, BP (Before Present) or YBP (years Before Present) are often used. (Present in this context by convention refers to January 1, 1950.) Write 3000 years BP or 3000 YBP or 3000 years before present but not forms such as 3000 before present and 3000 years before the present. If one of the abbreviated forms is used, link to Before Present on first use: The Jones artifact was dated to 4000 YBP, the Smith artifact to 5000 YBP.
• Other era systems may be appropriate in an article. In such cases, dates should be followed by a conversion to Anno Domini or Common Era, and the first instance linked: Qasr-al-Khalifa was built in 221 AH (836 CE), or in 836 AD (221 AH).
  • Astronomical year numbering is similar to the Common Era. There is no need to follow a year expressed with astronomical year numbering with a conversion to Common Era. The first instance of a non-positive year should still be linked: The March equinox passed into Pisces in year −67. (The expressions −67 and 68 BCE refer to the same year.)

Julian and Gregorian calendars

Shortcuts

• MOS:OSNS
• MOS:JG

A date can be given in any appropriate calendar, as long as it is (at the minimum) given in the Julian calendar or the Gregorian calendar or both, as described below. For example, an article on the early history of Islam may give dates in both Islamic and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.

• Current events are dated using the Gregorian calendar.
• Dates of events in countries using the Gregorian calendar at that time are given in the Gregorian calendar. This includes some of the Continent of Europe from 1582, the British Empire from 14 September 1752, and Russia from 14 February 1918 (see Adoption of the Gregorian calendar).
• Dates before 15 October 1582 (when the Gregorian calendar was first adopted in some places) are normally given in the Julian calendar.
• Dates after 4 October 1582 in a place where the Julian calendar was observed should be given in the Julian calendar.
• For either the Julian or Gregorian calendars, the beginning of the year should be treated as 1 January even if a different start-of-year date was observed in the place being discussed.
• Dates for Roman history before 45 BC are given in the Roman calendar, which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.
• For dates in early Egyptian and Mesopotamian history, Julian or Gregorian equivalents are often uncertain. Follow the consensus of reliable sources, or indicate their divergence.

The dating method used should follow that used by reliable secondary sources (or if reliable sources disagree, that used most commonly, with an explanatory footnote). The guidance above is in line with the usage of reliable sources such as American National Biography,^[1] Oxford Dictionary of National Biography, and Encyclopædia Britannica.^[i]

Where it is not obvious that a given date should be given in Julian alone or in Gregorian alone, consider giving both styles, for example by using {{OldStyleDate}}. If a date appears without being specified as Old Style or New Style, tagging that date with {{which calendar?}} will add the page to Category:Articles containing ambiguous dates for further attention.

If an article contains Julian calendar dates after 4 October 1582 (as in the October Revolution), or if a start-of-year date other than 1 January was in force in the place being discussed, or both, a footnote should be provided on the first usage, explaining the calendar usage adopted for the article. The calendar usage should be compatible with this guideline.

Ranges

Shortcuts

• MOS:DATERANGE
• MOS:DOB
• MOS:YEARRANGE

• A simple year–year range is written using an en dash (–, – or {{ndash}}, or {{nbnd}} for a non-breaking en dash), not an em dash, hyphen, or slash; this dash is unspaced (that is, with no space on either side); and the end year is usually given in full:
  • 1881–1882;  1881–1886 (not 1881–86);  1881–1892 (not 1881–92)
    • Markup: 1881{{ndash}}1882 or 1881–1882
  • Although non-abbreviated years are generally preferred, two-digit ending years (1881–82, but never 1881–882 or 1881–2) may be used in any of the following cases: (1) two consecutive years; (2) infoboxes and tables where space is limited (using a single format consistently in any given table column); and (3) in certain topic areas if there is a very good reason, such as matching the established convention of reliable sources.^[j] For consistency, avoid abbreviated year ranges when they would be used alongside non-abbreviated ranges within an article (or related pages, if in titles). Never use abbreviated years for ranges across centuries (1999–2000, not 1999–00) or for years from the first millennium (886–887, not 886–87).
  • The slash notation (2005/2006) may be used to signify a fiscal year or other special period, if that convention is used in reliable sources.
• Other "simple" ranges use an unspaced en dash as well:
  • day–day: 5–7 January 1979;  January 5–7, 1979;  elections were held March 5–8.
  • month–month: the 1940 peak period was May–July;  the peak period was May–July 1940;  (but the peak period was May 1940 – July 1940 uses a spaced en dash; see below)
• In certain cases where at least one item on either side of the en dash contains a space, then a spaced en dash ({{snd}}) is used. For example:
  • between specific dates in different months: They travelled June 3 – August 18, 1952;  They travelled 3 June – 18 August 1952
  • between dates in different years:
    • Charles Robert Darwin (12 February 1809 – 19 April 1882) was an English naturalist ...
      • Markup: 12{{nbsp}}February 1809{{snd}}19{{nbsp}}April 1882 or 12 February 1809 – 19 April 1882
    • Abraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th president of ...
  • between months in different years: The exception was in force August 1892 – January 1903;  The Ghent Incursion (March 1822 – January 1, 1823) was ended by the New Year's Treaty
    • Markup: March 1822{{snd}}January{{nbsp}}1, 1823 or March 1822 – January 1, 1823
  • Where era designations, c. or other modifiers are present (see § Uncertain, incomplete, or approximate dates):
    • if the modifier applies to only one of the two endpoints of the range, use a spaced en dash: 150 BCE – 50 BCE, 5 BC – 12 AD, c. 1393 – 1414
    • if the modifier applies to the range as a whole, disregard the modifier: 150–50 BCE, reigned 150 BCE – 50 BCE, reigned 150–50 BCE, r. c. 1393 – 1414, r. 1393–1414.
• Use an en dash, or a word such as from or between, but not both: from 1881 to 1886 (not from 1881–1886);  between June 1 and July 3 (not between June 1 – July 3)

Shortcuts

• MOS:DATETOPRES
• MOS:TOPRESENT

• MOS:DATED says "terms such as ... 'present' should usually be avoided". For ranges, if "to present" or "–present" is used, the current year (or, in cases where necessary, date) of "present" at the time of writing should be included. Thus 1982–present (as of 2024) – if writing in 2024 – is preferable to 1982–present. If the "from" date has an internal space, a spaced en dash is used. Other constructions may be more appropriate in prose (see § Statements likely to become outdated). An alternative form is Since 1982.

In tables and infoboxes where space is limited, pres. may be used (1982–pres.). Do not use incomplete-looking constructions such as 1982– and 1982–... .

• Consider adding the {{As of}}, or {{Update after}} templates to such constructions, depending on how important it is for editors to keep "present" up to date.

• For a person still living: Serena Williams (born September 26, 1981) is a ..., not (September 26, 1981 – ) or (born on September 26, 1981).

  Do not use * to indicate born; use b. only where space is limited e.g. tables and infoboxes; use either born or b. consistently in any given table column.

• Where birthdate is unknown: John Smith (died May 1, 1622) or John Smith (died 1622)

  Do not use † to indicate died; use d. only where space is limited, with consistency within any given table column.

• An overnight period may be expressed using a slash between two contiguous dates: the night raids of 30/31 May 1942 or raids of 31 May / 1 June 1942.

  Or use an en dash: (unspaced) raids of 30–31 May 1942;  (spaced) raids of 31 May – 1 June 1942.

• The {{Age}} template can keep ages current in infoboxes and so on:
  • {{age|1989|7|23}} returns: 34
  • {{age|1989|7|23}}-year-old returns: 34-year-old
  • {{age|1989|7|23}} years old returns: 34 years old
• Date mathematics templates are available for other age calculations.

Uncertain, incomplete, or approximate dates

Shortcuts

• MOS:APPROXDATE
• MOS:CIRCA

• To indicate "around", "approximately", or "about", the use of the {{circa}} template is preferred at first occurrence over just c.. At later occurrences, c. is preferred over circa, c, ca, ca., around, approximately, or approx.:
  • John Sayer (c. 1750 – 2 October 1818) ...
  • the Igehalkid dynasty of Elam, c. 1400 BC ...
• Where both endpoints of a range are approximate, c. should appear before each date (the two-argument form of {{circa}} does this):
  • Dionysius Exiguus (c. 470 – c. 540) ... (not Dionysius Exiguus (c. 470 – 540) ...)
  • Rameses III (reigned c. 1180 – c. 1150 BCE) ... (not Rameses III (reigned c. 1180 – 1150 BCE) ...)
• Where birth/death limits have been inferred from known dates of activity:
  • Offa of Mercia (before 734 – 26 July 796) ...
  • Robert Menli Lyon (1789 – after 1863) ...
  • Ambrose Gwinnett Bierce (June 24, 1842 – after December 26, 1913) ...
• When birth and death dates are unknown, but the person is known to have been active ("flourishing") during certain years, fl., [[Floruit|fl.]], or {{fl.}} may be used:
  • Jacobus Flori (fl. 1571–1588) ...
  • Jacobus Flori fils (fl. c. 1600 – 1616) ...

The corresponding template {{r.}} produces reign output: r. 540–562, though it is often clearer to write out reigned 540–562, especially in the lead. With both of these templates, linked forms should not be used on disambiguation pages, and "active" followed by the range is a better alternative for occupations not relating to the composition of works, whether it be musical, grammatical, historical, or any other such work.

• When a date is known to be either of two years (e.g. from a regnal or AH year conversion, or a known age at death):
  • Anne Smith (born 1912 or 1913; died 2013) ...
• Other forms of uncertainty should be expressed in words, either in article text or in a footnote: April 14, 1224 (unattested date). Do not use a question mark (1291?), because it fails to communicate the nature of the uncertainty.
• Where c. or a similar form appears which applies only to one of the two endpoints of the range, use a spaced en dash ({{snd}}).
  • Examples: 1896 – after 1954, 470 – c. 540, c. 470 – 540, c. 470 – c. 540.
  • Markup: 1896{{snd}}after 1954, 470{{snd}}{{c.|540}}, {{c.|470}}{{snd}}540, {{c.|470|540}}.
• Where a modifier applies to the range as a whole, such as fl. and r., use a spaced or unspaced en dash as appropriate to the range if this modifier is disregarded.
  • Examples: fl. 1571–1588, fl. c. 1600 – 1616, r. c. 1353 – 1336 BC, r. 1989–2019 CE, r. 2019 CE – present.
• Some modifiers, such as traditionally, around, BH, and CE, sometimes apply to only one endpoint, and sometimes to the whole range. Whether the en dash should be spaced or unspaced should still be determined by the above guidelines, but consider rephrasing if the result is ambiguous or possibly confusing.
  • traditionally 1571–1588 and traditionally 1571 – 1588 mean two different things, which may not be obvious to the reader.
  • traditionally 1585 – c. 1590 can have two different meanings, and which one is meant may not be clear.
  • 400 BCE – 200 clearly has BCE applying only to one endpoint, but the range is ambiguous. Consider using 400–200 BCE, 400 BCE – 200 BCE, or 400 BCE – 200 CE, depending on what is meant.
  • Technically, Taishō 13 – 57 is currently unambiguous (because there is no Taishō 57), but it is better to use both era designations in this case: Taishō 13 – Shōwa 57.
• Ideally a non-breaking space should follow very short modifiers such as c., fl., r., b., and d.

Times of day

Shortcuts

• MOS:TIME
• MOS:AMPM

Context determines whether the 12- or 24-hour clock is used. In all cases, colons separate hours, minutes, and (where present) seconds, e.g. 1:38:09 pm or 13:38:09. Use figures (11 a.m. or 12:45 p.m.) rather than words (twelve forty-five p.m.).

• 12-hour clock times end with lower-case a.m. or p.m., or am or pm, preceded by a non-breaking space, e.g. 2:30 p.m. or 2:30 pm (markup: 2:30{{nbsp}}p.m. or 2:30{{nbsp}}pm), not 2:30p.m. or 2:30pm. Hours should not have a leading zero (e.g. 2:30 p.m., not 02:30 p.m.). Usually, use noon and midnight rather than 12 pm and 12 am; whether "midnight" refers to the start or the end of a date should be explicitly specified unless clear from the context. Where several times that are all a.m. or all p.m. appear in close proximity, then a.m. or p.m. need be given only once if there is no risk of confusion.
• 24-hour clock times have no a.m., p.m., noon or midnight suffix, and include a colon (15:30 not 1530). Hours under 10 should have a leading zero (08:15). The time 00:00 refers to midnight at the start of a date, 12:00 to noon, and 24:00 to midnight at the end of a date, but 24 should not be used for the first hour of the next day (e.g. use 00:10 for ten minutes after midnight, not 24:10).

Time zones

Shortcut

• MOS:TIMEZONE

Give dates and times appropriate to the time zone where an event took place. For example, the date of the attack on Pearl Harbor should be December 7, 1941 (Hawaii time/​date). Give priority to the place at which the event had its most significant effects; for example, if a hacker in Monaco attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases, the best solution may be to add the date and time in Coordinated Universal Time (UTC). For example:

     8 p.m. Eastern Standard Time on January 15, 2001 (01:00 UTC, January 16)

Alternatively, include just the UTC offset:

     21:00 British Summer Time (UTC+1) on 27 July 2012

Rarely, the time zone in which an event took place has since changed; for example, China until 1949 was divided into five time zones, whereas all of modern China is one time zone; UTC+8. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1960;^[2] Universal Time (UT) is the appropriate term for the mean time at the prime meridian (Greenwich) when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.

Days of the week

• Where space is limited (e.g. tables), days of the week may be abbreviated as Sun, Mon, Tue, Wed, Thu, Fri, Sat (without dots, i.e. not Sun., Mon., etc.).

Seasons of the year

Shortcut

• MOS:SEASON

• Avoid using seasons to refer to a particular time of year, as they are often unduly ambiguous: Spring 1995 began in the Southern Hemisphere six months after it did in the Northern Hemisphere; winter spans two calendar years in the Northern Hemisphere, but not in the Southern Hemisphere. Moreover, areas near the Equator have only wet and dry seasons. Unambiguous alternatives include early 1995; the second quarter of 1995; March to June 1995; spent the southern autumn in Antarctica.
  • Referring to a season by name is appropriate when it is part of a conventional name or designation (annual mid-winter festival; the autumn harvest; the court's winter term; the magazine's summer 2015 issue).
• Season names are generally not capitalized (a hot summer), except when personified (Old Man Winter) or when part of a formal name (2018 Winter Olympics; Arab Spring) that is capitalized under the guidelines for capitalization. They are capitalized when part of the title of a work (Science Fiction Quarterly, Summer 1942), except that seasonal editions may be lower-cased in running text (the Summer 1985 issue of Interzone or the summer 1985 issue of Interzone).

Decades

Shortcuts

• MOS:DECADE
• MOS:DECADES

• To refer to a decade as a chronological period per se (not with reference to a social era or cultural phenomenon), always use four digits and an s, as in the 1980s. Do not use the 1980's, or the 1980‑ies.
  • Prefixes should be hyphenated (the mid‑1980s;  pre‑1960s social attitudes).
  • Adjectives should not be hyphenated (the late 1950s, the early 1970s).
• For a social era or cultural phenomenon associated with a particular decade:
  • Two digits (with a preceding apostrophe) may be used as an alternative to four digits, but only in well-established phrases seen in reliable sources: the Roaring '20s; the Gay '90s; condemning the '60s counterculture—but grew up in 1960s Boston, moving to Dallas in 1971. Do not write: the 90's; the 90s; or the 90s'.
  • Another alternative (where seen in reliable sources) is to spell the decade out, capitalized: changing attitudes of the Sixties.

Centuries and millennia

Shortcuts

• MOS:CENTURY
• MOS:MILLENNIUM

The sequence of numbered years in dates runs ... 2 BC, 1 BC, 1 AD, 2 AD ...; there is no "year zero".

• Treat the 1st century AD as years 1–100, the 17th century as 1601–1700, and the second millennium as 1001–2000; similarly, the 1st century BC / BCE was 100–1 BC / BCE, the 17th century BC / BCE was 1700–1601 BC / BCE, and the second millennium 2000–1001 BC / BCE.
• Centuries and millennia are identified using either Arabic numerals (the 18th century) or words (the second millennium), with in-article consistency (MOS:ORDINAL notwithstanding). When used adjectivally they contain a hyphen (nineteenth-century painting or 19th-century painting). Do not use superscripts (19^th century).
• Do not capitalize (the best Nineteenth-century paintings; during the Nineteenth Century)
• Do not use Roman numerals (XVIII century).
• The 18th century refers to the period (1701–1800), while strictly the 1700s refers either to (1700–1799) or (1700–1709)
  • When using forms such as the 1900s, ensure there is no ambiguity as to whether the century or the decade is meant.
• See WP:Manual of Style § En dashes for use of hyphens and dashes in obscure situations.

Long periods of time

• When the term is frequent, combine yr (years) or ya (years ago) with k (thousand): kya, kyr; M (million): Mya, Myr; and b (short-scale billion): bya, byr. (See Year § Abbreviations yr and ya for more information.)
• In academic contexts, annus-based units are often used with an SI prefix: ka (kiloannus), Ma (megaannus), and Ga (gigaannus). (See Year § SI prefix multipliers for more information.)
• Show the meaning parenthetically, and consider linking to the appropriate section of the Year article (Year § Abbreviations yr and ya or Year § SI prefix multipliers) on first occurrence and where the use is a standalone topic of interest. In source quotations, use square brackets: "a potassium-argon date of 35.1 Mya [million years ago] ..."

Numbers

Numbers as figures or words

Shortcuts

• MOS:NUMERAL
• MOS:SPELL09
• MOS:MILLION
• MOS:BILLION
• MOS:TRILLION
• MOS:LAKH
• MOS:CRORE

Information on specific situations is scattered elsewhere on this page.

Generally, in article text:

• Integers from zero to nine are spelled out in words.
• Integers greater than nine expressible in one or two words may be expressed either in numerals or in words (16 or sixteen, 84 or eighty-four, 200 or two hundred). When written as words, integers from 21 to 99 that are not multiples of 10 are hyphenated (including when part of a larger number): fifty-six and fifty-six thousand, but five hundred and five thousand.

Shortcut

• MOS:NUMNOTES

Notes and exceptions:

• Avoid beginning a sentence with a figure:
  • Use: There were many matches; 23 ended in a draw. Or: There were many matches. Twenty-three ended in a draw.
  • Not: There were many matches. 23 ended in a draw.
  • Use: No elections were held in 1945 and 1950.
  • Not: 1945 and 1950 had no elections. (Nor: Nineteen forty-five and 1950 had no elections – comparable numbers should be both written in words or both in figures.)
• In tables and infoboxes, quantities are expressed in figures (Years in office: 5); but numbers within a table's explanatory text and comments follow the general rule.
• Numbers in mathematical formulae are never spelled out (3 < π < ⁠22/7⁠ not three < pi < twenty-two sevenths), and "numbers as numbers" are rarely spelled out in other mathematical contexts (the first three primes are 2, 3, and 5 not the first three primes are two, three, and five; but zero-sum game and roots of unity).
• Sport scores and vote tallies should be given as numerical figures (a 25–7 victory; passed with 7 ayes, 2 nays, and 1 abstention, though passed with 7 ayes, 2 nays, and no abstentions would be acceptable, instead of ... 0 abstentions).
• Comparable values nearby one another should be all spelled out or all in figures, even if one of the numbers would normally be written differently: patients' ages were five, seven, and thirty-two or ages were 5, 7, and 32, but not ages were five, seven, and 32.
  • Similar guidance applies where "mixed units" are used to represent a single value (as is often done with time durations, and in the imperial and US customary systems): 5 feet 11 inches tall; five feet eleven inches tall; 3 minutes 27 seconds; three minutes twenty-seven seconds.
• Adjacent quantities not comparable should ideally be in different formats: twelve 90-minute volumes or 12 ninety-minute volumes, not 12 90-minute volumes or twelve ninety-minute volumes.
  • Avoid awkward juxtapositions: On February 25, 2011, twenty-one more were chosen, not On February 25, 2011, 21 more were chosen.
• Sometimes figures and words carry different meanings; for example, Every locker except one was searched implies there is a single exception (without specifying which), while Every locker except 1 was searched implies that locker number 1 was the only locker not searched.
• Proper names, technical terms, and the like are never altered: 10 Downing Street,  Nine Inch Nails,  Channel 8,  Seven Samurai,  The Sixth Sense,  Chanel No. 5,  Fourth Estate,  The Third Man,  Second Coming,  First Amendment,  Zero Hour!,  "Less than Zero",  C7 vertebra.
• Figures as figures: Use a figure when the figure itself (its glyph, shape, etc.) is meant: a figure-8 pattern; in the shape of the numeral 6. (See Wikipedia:Manual of Style/Text formatting § Words as words.)
• Only figures are used with unit symbols (12 min not twelve min); but figures or words may be used with unit names (12 minutes or twelve minutes), subject to the provisions above.

Other numbers

• Other numbers are given in numerals (3.75, 544) or in forms such as 21 million (or billion, trillion, etc. – but rarely thousand or hundred). Markup: 21{{nbsp}}million
  • Billion and trillion are understood to represent their short-scale values of 10⁹ (1,000,000,000) and 10¹² (1,000,000,000,000), respectively. Keep this in mind when translating articles from non-English or older sources.
  • M (unspaced, capitalized) or bn (unspaced), respectively, may be used for "million" or "billion" after a number, when the word has been spelled out at the first occurrence (Her estate of £61 million was split among her husband (£1M), her son (£5M), her butler (£10M), and her three Weimaraners (£15M each).).
  • SI prefixes and symbols, such as mega- (M), giga- (G) and tera- (T), should be used only with units of measure as appropriate to the field and not to express large quantities in other contexts. Examples of misuse: In a population of 1.3G people, 300 megadeaths would be expected.
  • Sometimes, the variety of English used in an article may suggest the use of a numbering system other than the Western thousands-based system. For example, the Indian numbering system is conventionally used for certain things (especially monetary amounts) in South Asian English. This is discouraged in Wikipedia articles by WP:Manual of Style § Opportunities for commonality.
    • When it is done anyway, for contextually important reasons, link the first spelled-out instance of each quantity (e.g. [[crore]], which yields: crore). If no instances are spelled out, provide a note after the first instance, directing the reader to the article about the numbering system.
    • Provide a conversion to Western numbers for the first instance of each quantity (For Indian figures, the templates {{lakh}} and {{crore}} may be used for this purpose), and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write three crore (thirty million). When converting a currency amount, use the exchange rate that applied at the time being written about; the {{FXConvert}} template can be used for this purpose, or specialized templates for a currency such as {{INRConvert}} (for Indian Rupees) or {{KRWConvert}} (for Korean Won) can be used.
    • Group digits in Western thousands-based style (e.g., 30,000,000; not 3,00,00,000); see § Delimiting (grouping of digits), below.
    • An article's variety of English does not uniquely determine its formatting of numbers. Other considerations – such as conventions used in mathematics, science, and engineering – may also apply. In general, choice and order of formats and conversions is a matter of editorial discretion and consensus at the article.

Shortcut

• MOS:ORDINAL

Ordinals

• The general principles set out in § Numbers as figures or words apply to ordinals. In particular, do not start a sentence with a figure, and generally use first through ninth, not 1st through 9th, for single-digit ordinals.
• In "suffix" forms, use two-letter suffixes: 1st, 2nd, 3rd, 4th and so on (2nd Battalion not 2d Battalion). Do not superscript (e.g. 123^rd).
• Do not use ordinals for dates (see MOS:BADDATE).
• In English text, do not use a dot (.) or the ordinal indicator (º). The masculine º or feminine ª ordinal indicator is acceptable in names, quotations, etc. from languages that conventionally use it. An Italian example: 313º Gruppo Addestramento Acrobatico not 313º Acrobatic Training Group or the 313º. Use HTML markup for languages that do not have a special character but conventionally use a superscript, like 2^e in French.
• Regnal numbers are normally written with ASCII Roman numerals (without suffix, e.g. Elizabeth II not Elizabeth IInd or Elizabeth 2nd).

Number ranges

Shortcuts

• MOS:NUMRANGE
• MOS:PAGERANGE

Like date ranges, number ranges and page ranges should state the full value of both the beginning and end of the range, separated by an en dash: pp. 1902–1911 or entries 342–349. Except within quotations, avoid abbreviated forms such as 1902–11 or 342–9, which are not understood universally, are sometimes ambiguous, and can cause inconsistent metadata to be created in citations.

Sport scores, vote tallies, etc.

Shortcuts

• MOS:VOTE
• MOS:SCORES

Sport scores, vote tallies, or other presentations that juxtapose two opposing quantities use an unspaced en dash:

• Smith beat Jones 7–3.
• Polls predicted Alice would defeat Bob 74–20 percent, with 6 percent undecided.

To avoid potential line breaks, use {{nowrap}} around the entire score construction, or use {{nbnd}} instead of {{ndash}}.

Singular versus plural

• Nouns following simple fractions are singular (took 1⁄4 dose;  net change was −1⁄2 point;  3⁄2 dose).
• Nouns following mixed numbers are plural (11⁄2 doses;  another 43⁄4 miles).
• Nouns following the lone, unsigned digit 1 (one) are singular, but those following other decimal numbers (i.e. base-10 numbers not involving fractions) are plural (increased 0.7 percentage points;  365.25 days;  paid 5 dollars per work hour, 1 dollar per travel hour, 0 dollars per standby hour;  increased by 1 point but net change +1 points;  net change −1 points;  net change 1.0 points).
• The same rules apply to numbers given in words (one dose;  one and one-half doses;  zero dollars;  net change of negative one points).

Fractions and ratios

Shortcuts

• MOS:FRAC
• MOS:RATIO

• Where numerator and denominator can each be expressed in one word, a fraction is usually spelled out (e.g. a two-thirds majority;  moved one-quarter mile); use figures if a fraction appears with a symbol (e.g. 1⁄4 mi (markup: {{frac|1|4}} mi), not a quarter of a mi or one-quarter mi). A common exception is a series of values: The distances were 1+1⁄4, 2⁄3 and 1⁄2 mile, respectively.
• Mixed numbers may be given in figures or words (perhaps applying the guidance above to the integer part). If given in figures, they are unspaced (not Platform 9 3⁄4 or Platform 9-3⁄4 but Platform 9+3⁄4 (markup: {{frac|9|3|4}})). In any case the integer and fractional parts should be consistent (not Platform nine and 3⁄4).
• Metric (SI) measurements generally use decimals, not fractions (5.25 mm, not 51⁄4 mm).
• Non-metric (imperial and US customary) measurements may use fractions or decimals (51⁄4 inches; 5.25 inches); the practice of reliable sources should be followed, and within-article consistency is desirable.
• In science and mathematics articles, mixed numbers are rarely used (use ⁠4/3⁠ the original rather than 1⁠1/3⁠ times the original voltage). The use of {{frac}} is discouraged; instead use one of these styles:
  • ${\displaystyle \textstyle {\frac {1}{2}}}$ (markup: <math>\textstyle\frac{1}{2}</math>)
  • ⁠1/2⁠ (markup: {{sfrac|1|2}})
  • 1/2 (markup: 1/2)
• Do not use precomposed fraction characters such as ½ (deprecated markup: &frac12; or &#189;).^[k]
  • Except: If ¼, ½, and ¾^[l] are the only fractions needed, they may be used in an article, or category name, maintaining typographical consistency within an article where possible. (Examples: Floppy disk, Ranma ½, chess notation, Category:4 ft 6½ in gauge railways‎.)
  • For other fractions, where templates cannot be used due to technical limitations, use the ASCII representation with spaces. For example, Category:4 ft 10 7/8 in gauge railways.
• Ordinal suffixes such as -th should not be used with fractions expressed in figures (not each US state has 1/50th of the Senate's votes; 1/8th mile, but one-fiftieth of the Senate's votes; 1/8 mile; one-eighth mile).
• For dimensionless ratios (i.e. those without accompanying units), place a colon between integers, or place to between numbers-as-words: favored by a 3:1 ratio or a three-to-one ratio, not a 3/1 ratio or a 3–1 ratio. The same style is used to express odds in sport, gambling, and other statistical predictions.
  • Use a colon (spaced) when one or more decimal points is present (a 3.5 : 1 ratio (markup: a 3.5 : 1 ratio)).
  • Do not use the colon form where units are involved (dissolve using a 3 ml : 1 g ratio)‍—‌instead see ratios section of table at § Unit names and symbols, below.

Decimals

Shortcut

• MOS:DECIMAL

• Use a period/full point (.) as the decimal separator, never a comma: 6.57, not 6,57.
• Numbers between −1 and +1 require a leading zero (0.02, not .02); exceptions are sporting performance averages (.430 batting average) and conventional terms such as .22 caliber.
• Although repeating digits may be indicated with an overbar (e.g. 14.31{{overline|28}} gives 14.3128), users of screen readers will not hear any indication of the overbar. Apart from in mathematics articles, consider rounding to a reasonable resolution instead (e.g. a half farthing ≈£0.00052 not £0.00052083, an inch ≈0.333 palms not 0.3 palms), or showing initial repeats before the overbar (e.g. 0.333). If overbars are used, consider explaining the notation on first use. Do not write e.g. 14.31(28) because it resembles notation for uncertainty.

Grouping of digits

Shortcut

• MOS:DIGITS

• In general, digits should be grouped and separated either by commas or by narrow gaps (never a period/full point).
  • Grouping with commas
    • Left of the decimal point, five or more digits are grouped into threes separated by commas (e.g. 12,200; 255,200 km; 8,274,527th; 1⁄86,400).
    • Numbers with exactly four digits left of the decimal point may optionally be grouped (either 1,250 or 1250), consistently within any given article.
    • Do not use commas to the right of the decimal point, or with numbers not in base 10.
    • Markup: {{formatnum:}} produces this formatting.
  • Grouping with narrow gaps
    • Digits are grouped both sides of the decimal point (e.g. 6543210.123456; 520.01234 °C; ⁠101325/760⁠).
    • Digits are generally grouped into threes. Right of the decimal point, usual practice is to have a final group of four in preference to leaving an "orphaned" digit at the end (99.1234567, but 99.1234567 would also be acceptable). In mathematics-oriented articles long strings may be grouped into fives (e.g. 3.14159265358979323846...).
    • This style is especially recommended for articles related to science, technology, engineering or mathematics, though in these contexts there may be cases in which grouping confuses rather than clarifies. (For example, for fractions written in horizontal format, adding spaces to a fraction like 123456/127 would cause it to be misread as 123⁠456/127⁠ or 1⁠23456/127⁠.)
    • Markup: Templates {{val}} or {{gaps}} may be used to produce this formatting. Note that use of any space character as a separator in numbers, including non-breaking space, is problematic for screen readers. (See § Non-breaking spaces.) Screen readers read out each group of digits as separate numbers (e.g. 30{{thin space}}000 is read as "thirty zero zero zero"). The output of {{val}} and {{gaps}} is compatible with screen readers.
• Delimiting style should be consistent throughout a given article.
  • Either use commas or narrow gaps, but not both in the same article.
  • Either group the thousands in a four-digit number or do not, but not mixed use in the same article.
  • However, grouping by threes and fives may coexist.
• Four-digit page numbers and four-digit calendar years should never be grouped (not sailed in 1,492, but dynasty collapsed around 10,400 BC or by 13727 AD, Vega will be the northern pole star).

Percentages

Shortcuts

• MOS:PERCENT
• MOS:%

• Throughout scientific/​technical articles, and in tables and infoboxes in any article, the symbol % is generally preferred. Omit space (3%, not 3 %), and do not use mixed forms such as three %.
• The body^[h] of non-scientific/​non-technical articles may use either the % symbol or the word(s) percent (American English) or per cent (British English): 10 percent; ten percent; 4.5 per cent.
• Ranges are written 10–12%, ten to twelve per cent, or ten to twelve percent; not ten–twelve per cent, 10%–12%, or 10 to 12%.
• When expressing the difference between two percentages, do not confuse a percentage change with a change in percentage points.

Scientific and engineering notation

Shortcuts

• MOS:SCIENGNOTATION
• MOS:10^X

• Scientific notation always has a single nonzero digit to the left of the point: not 60.22×10²², but 6.022×10²³.
• Engineering notation is similar, but with the exponent adjusted to a multiple of three: 602.2×10²¹.
• Avoid mixing scientific and engineering notations: A 2.23×10² m² region covered by 234.0×10⁶ grains of sand.
• In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g. ×10⁷ once in the column header, and omitting it in the individual entries. (Markup: {{e|7}})
• In both notations, the number of digits indicates the precision. For example, 5×10³ means rounded to the nearest thousand; 5.0×10³ to the nearest hundred; 5.00×10³ to the nearest ten; and 5.000×10³ to the nearest unit.

Markup: {{val}} and {{e}} may be used to format exponential notation.

Uncertainty and rounding

Shortcuts

• MOS:UNCERTAINTY
• MOS:LARGENUM

• Where explicit uncertainty information (such as a margin of error) is available and appropriate for inclusion, it may be written in various ways:
  • (1.534 ± 0.035) × 10²³ m
  • 12.34 m² ± 5% (not used with scientific notation)
  • 15.34 ^+0.43
    _−0.23 × 10²³ m
  • 1.604(48) × 10⁻⁴ J (equivalent to (1.604 ± 0.048) × 10⁻⁴ J)^[m]
  • Polls estimated Jones's share of the vote would be 55 percent, give or take about 3 percent
  • Markup: {{+-}}, {{su}}, and {{val}} may be used to format uncertainties.
• Where explicit uncertainty is unavailable (or is unimportant for the article's purposes), round to an appropriate number of significant digits; the precision presented should usually be conservative. Precise values (often given in sources for formal or matter-of-record reasons) should be used only where stable and appropriate to the context, or significant in themselves for some special reason.
  • The speed of light is defined to be 299,792,458 m/s
  • but Particle velocities eventually reached almost two-thirds the 300-million-metre-per-second speed of light.
  • checks worth $250 (equivalent to $1,800 in 2016) (not $1,845.38 in 2016)
  • The city's 1920 population was 10,000 (not population was 9,996 – an official figure unlikely to be accurate at full precision)
  • but The town was ineligible because its official census figure (9,996) fell short of the statutory minimum of ten thousand (unusual case in which the full-precision official figure is truly informative)
  • The accident killed 337 passengers and crew, and 21 people on the ground (likely that accurate and precise figures were determined)
  • At least 800 persons died in the ensuing mudslides (unlikely that any precise number can be accurate, even if an official figure is issued)
  • or Officials listed 835 deaths, but the Red Cross said dozens more may have gone unreported (in reporting conflicting information, give detail sufficient to make the contrast intelligible)
  • The jury's award was $8.5 million (not $8,462,247.63). The appeals court reduced this to $3,000,001 (one dollar in actual damages, the remainder in punitive damages).
• The number of decimal places should be consistent within a list or context (The response rates were 41.0 and 47.4 percent, respectively, not 41 and 47.4 percent), unless different precisions are actually intended.
• It may sometimes be appropriate to note the lack of uncertainty information, especially where such information is normally provided and necessary for full interpretation of the figures supplied.
  • A local newspaper poll predicted 52 percent of the vote would go to Smith, but did not include information on the uncertainty of this estimate
• The {{undue precision}} template may be added to figures appearing to be overprecise.
• Avoid using "approximately", "about", and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.
  • The tallest player was 6 feet 3 inches (not ... about 6 feet 3 inches – heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle)
  • but The witness said the assailant was about 5 feet 8 inches tall ("about" because here the precise value is unknown, with substantial uncertainty)
• The reader may be assumed to interpret large round numbers (100,000 troops) as approximations. Writing a quantity in words (one hundred thousand troops), especially if the indefinite article (a/an) is used instead of the word one (a hundred thousand troops), can further emphasize its approximate nature.
• See § Unit conversions below for precision issues when converting units.

Non–base-10 notations

Shortcuts

• MOS:BASE
• MOS:RADIX
• MOS:BINARY
• MOS:HEX

• In computer-related articles, use the prefix 0x for hexadecimal and 0b for binary,^[n] unless there is a strong reason to use some other notation.^[o] Explain these prefixes in the article's introduction or on first use.
• In all other articles, use {{base}}: 137₉, 201₃. Markup: {{base|137|9}}, {{base|201|3}}
• For bases above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for base 16 use 0–9 and A–F.
• For octal, use 200₈. Avoid using a prefix unless it is needed for computer code samples, in which case explain the prefix on first use.

Mathematical formulae

There are multiple ways to display mathematical formulae, covered in detail at Wikipedia:Manual of Style/Mathematics § Typesetting of mathematical formulae. One uses special MediaWiki <math>...</math> markup using LaTeX syntax, which is capable of complex formulae; the other relies on conventionalized HTML formatting of simple formulae.

The <math> markup is displayed as a PNG image by default. Logged-in users can optionally have it rendered in MathML, or in HTML (via MathJax); detailed instructions are at Help:Displaying a formula.

Do not put <math> markup in headings.

Units of measurement

Shortcuts

• MOS:UNIT
• MOS:UNITS
• MOS:METRIC
• MOS:MEASUREMENT

Unit choice and order

Quantities are typically expressed using an appropriate "primary unit", displayed first, followed, when appropriate, by a conversion in parentheses e.g. 200 kilometres (120 mi). For details on when and how to provide a conversion, see the section § Unit conversions. The choice of primary units depends on the circumstances, and should respect the principle of "strong national ties", where applicable:

• In non-scientific articles with strong ties to the United States, the primary units are US customary (pounds, miles, feet, inches, etc.)
• In non-scientific articles with strong ties to the United Kingdom, the primary units for most quantities are metric or other internationally used units,^[p] except that:
  • UK engineering-related articles, including those on bridges and tunnels, generally use the system of units in which the subject project was drawn up (but road distances are given in imperial units, with a metric conversion – see next bullet);
  • the primary units for distance/​length, speed and fuel consumption are miles, miles per hour, and miles per imperial gallon (except for short distances or lengths, where miles are too large for practical use);
  • the primary units for personal height and weight are feet​/inches and stones/​pounds;
  • imperial pints are used for quantities of draught beer/​cider and bottled milk;
• In all other articles, the primary units chosen will be SI units (such as kilograms), non-SI units officially accepted for use with the SI, or such other units as are conventional in reliable-source discussions of the article topic (such as revolutions per minute (rpm) for rotational speed, hands for heights of horses, etc.)
  • the primary SI units for personal height and weight are centimetres and kilograms.

Special considerations:

• Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent: During metrication, the speed limit was changed from 30 mph (48 km/h) to 50 km/h (31 mph).
  • Or use about to emphasize which is the statutory, exact value: ...from 30 mph (about 48 km/h) to 50 km/h (about 31 mph).
• Nominal quantities (e.g. 2 × 4 lumber) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases, the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.
• Whenever a conversion is given, the converted quantity's value should match the precision of the source (see § Unit conversions).
• Where the article's primary units differ from the units given in the source, the {{convert}} template's |order=flip flag can be used; this causes the original unit to be shown as secondary in the article, and the converted unit to be shown as primary: {{convert|200|mi|km|order=flip}} → The two cities are 320 kilometres (200 mi) apart.

Unit conversions

Shortcuts

• MOS:CONVERSIONS
• MOS:CVT

Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses: the Mississippi River is 2,320 miles (3,734 km) long; the Murray River is 2,508 kilometres (1,558 mi) long. But in science-related articles, supplying such conversion is not required unless there is some special reason to do so.

• Where an imperial unit is not part of the US customary system, or vice versa – and in particular, where those systems give a single term different definitions – a double conversion may be appropriate: Rosie weighed 80 kilograms (180 lb; 12 st 8 lb) (markup: {{convert|80|kg|lb stlb}}); The car had a fuel economy of 5 L/100 km (47 mpg_‑US; 56 mpg_‑imp) (markup: {{convert|5|L/100km|mpgus mpgimp|abbr=on}}).
• Generally, conversions to and from metric units and US or imperial units should be provided, except:
  • When inserting a conversion would make a common or linked expression awkward (The four-minute mile).
  • In some topic areas (for example maritime subjects where nautical miles are the primary units, or American football where yards are primary) it can be excessive to provide a conversion for every quantity. In such cases consider noting that the article will use a particular unit – possibly giving the conversion factor to other, familiar units in a parenthetical note or a footnote – and link the first occurrence of each unit but not give a conversion every time it occurs. Applying this principle may require editorial discretion; for example, in scientific articles the expected level of reader sophistication should be taken into account.
• For units of measure that are obsolete, obscure outside of a particular specialty or geography (e.g. furlong), or not part of the SI or US customary systems (e.g. zolotnik), supply a parenthetical conversion into at least SI units. Convert each mention, unless this would be excessive given the context. Take care to distinguish between different definitions of the same unit if it has changed over time or differs geographically (e.g. cubit, batman). An approximate or range conversion is acceptable if the exact historical value is uncertain (e.g. stadion).
• Converted quantity values should use a level of precision similar to that of the source quantity value, so the Moon is 380,000 kilometres (240,000 mi) from Earth, not (236,121 mi). Small numbers, especially if approximate, may need to be converted to a range where rounding would cause a significant distortion, so about one mile (1–2 km), not about one mile (2 km). Be careful especially when your source has already converted from the units you're now converting back to. This may be evidenced by multiples of common conversion factors in the data, such as 160 km (from 100 miles). See false precision.
• {{convert}} and other conversion templates can be used to convert and format many common units, and have options to respect significant figures. To avoid problems with rounding and significant figures, for input to conversion templates use only the original quantity found in reliable sources, not one that a source has already converted. If required by the above rules, the conversion output can be displayed as the primary units with "order=flip". Conversion output can be displayed as the only units with "disp=out"; this retains the original quantity in wikitext for verification by editors.
• In a direct quotation, always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote. See footnoting and citing sources.
• {{Units attention}} may be added to articles needing general attention regarding choice of units and unit conversions.

Unit names and symbols

Shortcuts

• MOS:UNITNAMES
• MOS:UNITSYMBOLS

Definitions:

• Examples of unit names: foot, metre, kilometre, (US: meter, kilometer).
• Examples of unit symbols: ft, m, km.

• Unit names and symbols should follow the practice of reliable sources.
• In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g. Up to 15 kilograms of filler is used for a batch of 250 kg).
  • Exception: Certain units are generally represented by their symbols (e.g. °C rather than degrees Celsius) even on first use, though their unit names may be used for emphasis or clarity (conversion of degrees Celsius to degrees Fahrenheit).
  • Exception: Consider using inches (but not in.) in place of in where the latter might be misread as a preposition‍—‌but not where the value is followed by a parenthesized conversion e.g. bolts 5 in (12.7 cm) long, or is part of such a conversion (bolts 12.7 cm (5 in) long).
• Where space is limited, such as in tables, infoboxes, parenthetical notes, and mathematical formulas, unit symbols are preferred.
• Units unfamiliar to general readers should be presented as a name–symbol pair on first use, linking the unit name (Energies rose from 2.3 megaelectronvolts (MeV) to 6 MeV).
• Ranges use unspaced en dash ({{ndash}}) if only one unit symbol is used at the end (e.g. 5.9–6.3 kg), and spaced en dash ({{snd}}) if two symbols are used (e.g. 3 μm – 1 mm); ranges in prose may be specified using either unit symbol or unit names, and units may be stated either after both numerical values or after the last (all acceptable: from 5.9 to 6.3 kilograms; from 5.9 kilograms to 6.3 kilograms; from 5.9 to 6.3 kg; from 5.9 kg to 6.3 kg).
• Length–width, length–width–height and similar dimensions may be separated by the multiplication sign (× or ×) or the word by.
  • The × symbol is preceded by a space (preferably non-breaking), and followed by a space (which may also be non-breaking in short constructions), and each number should be followed by a unit name or symbol:
    • 1 m × 3 m × 6 m, not 1 × 3 × 6 m, (1 × 3 × 6) m, nor 1 × 3 × 6 m³
    • a metal plate 1 ft × 3 ft × 0.25 in
    • a railroad easement 10 ft × 2.5 mi
  • With by, the unit need be given only once if it is the same for all dimensions: 1 by 3 by 6 metres or 1 by 3 by 6 m
  • The unspaced letter x may be used in common terms such as 4x4.

Note to table:

1. Use this format only where it is clear from context whether it means hours and minutes (HH:MM) or minutes and seconds (MM:SS).
2. This format is used in astronomy (see the IAU Style Manual^[6] for details).

Specific units

Shortcuts

• MOS:FOOT
• MOS:INCH

• The following table lists only units that need special attention.
• The SI Brochure^[4] should be consulted for guidance on use of other SI and non-SI units.

Quantities of bytes and bits

Shortcut

• MOS:COMPUNITS

In quantities of bits and bytes, the prefixes kilo- (symbol k or K), mega- (M), giga- (G), tera- (T), etc., are ambiguous in general usage. The meaning may be based on a decimal system (like the standard SI prefixes), meaning 10³, 10⁶, 10⁹, 10¹², etc., or it may be based on a binary system, meaning 2¹⁰, 2²⁰, 2³⁰, 2⁴⁰, etc. The binary meanings are more commonly used in relation to solid-state memory (such as RAM), while the decimal meanings are more common for data transmission rates, disk storage and in theoretical calculations in modern academic textbooks.

Follow these recommendations when using these prefixes in Wikipedia articles:

• Following the SI standard, a lower-case k should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital K should be used instead to indicate the binary prefix for 1024 according to JEDEC. If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use Ki instead.
• Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article ({{BDprefix}} is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
• The definition most relevant to the article should be chosen as primary for that article, e.g. specify a binary definition in an article on RAM, decimal definition in an article on hard drives, bit rates, and a binary definition for Windows file sizes, despite files usually being stored on hard drives.
• Where consistency is not possible, specify wherever there is a deviation from the primary definition.
• Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
  • A 64 MB (64 × 1024²-byte) video card and a 100 GB (100 × 1000³-byte) hard drive
  • A 64 MB (64 × 2²⁰-byte) video card and a 100 GB (100 × 10⁹-byte) hard drive
  • A 64 MB (67,108,864-byte) video card and a 100 GB (100,000,000,000-byte) hard drive
• Avoid combinations with inconsistent form such as A 64 MB (67,108,864-byte) video card and a 100 GB (100 × 1000³-byte) hard drive. Footnotes, such as those seen in Power Macintosh 5500, may be used for disambiguation.
• Unless explicitly stated otherwise, one byte is eight bits (see Byte § History).
• Shortcut

  • MOS:BINPREFIX
  The IEC prefixes kibi- (symbol Ki), mebi- (Mi), gibi- (Gi), etc., are generally not to be used except:^[r]
  • when the majority of cited sources on the article topic use IEC prefixes;
  • in a direct quote using the IEC prefixes;
  • when explicitly discussing the IEC prefixes; or
  • in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.

Currencies and monetary values

Shortcuts

• MOS:$
• MOS:£
• MOS:€
• MOS:CURRENCY
• MOS:MONEY

Choice of currency

• In country-specific articles, such as Economy of Australia, use the currency of the subject country.
• In non-country-specific articles, such as Wealth, use US dollars (US$123 on first use, generally $123 thereafter), euros (€123), or pounds sterling (£123).

Currency names

• Do not capitalize the names or denominations of currencies, currency subdivisions, coins and banknotes: not a Five-Dollar bill, four Quarters, and one Penny total six Dollars one Cent but a five-dollar bill, four quarters, and one penny total six dollars one cent. Exception: where otherwise required, as at the start of a sentence or in such forms as Australian dollar.
• To pluralize euro, use the standard English plurals (ten euros and fifty cents), not the invariant plurals used for European Union legislation and banknotes (ten euro and fifty cent). For the adjectival form, use a hyphenated singular (a two-euro pen and a ten-cent coin).
• Link the first occurrence of lesser-known currencies (e.g. Mongolian tögrögs).

Currency symbols

• In general, the first mention of a particular currency should use its full, unambiguous signifier (e.g. A$52), with subsequent references using just the appropriate symbol (e.g. $88), unless this would be unclear. Exceptions:
  • In an article referring to multiple currencies represented by the same symbol (e.g. the dollars of the US, Canada, Australia, New Zealand, and other countries – see Currency symbols § dollar variants) use the full signifier (e.g. US$ or A$, but not e.g. $US123 or $123 (US)) each time, except (possibly) where a particular context makes this both unnecessary and undesirable.
  • In articles entirely on US-related topics, all occurrences of the US dollar may be shortened ($34), unless this would be unclear.
  • For currencies that use a unit named the "pound":
    • Use the £ symbol (U+00A3 £ POUND SIGN) for unambiguous referrals to sterling, the United Kingdom's currency. Avoid the U+20A4 ₤ LIRA SIGN.^[s]
    • GBP, sterling's ISO 4217 code, should be used to disambiguate that currency from others. Avoid using stg. or GB£.^[t]
    • For currencies other than sterling, use the symbol or abbreviation conventionally employed for that currency, if any.
• Link the first occurrence of lesser-known currency symbols (e.g. ₮)
• If there is no common English abbreviation or symbol, follow the ISO 4217 standard. See also List of circulating currencies.

Currency formatting

• A point (full stop or period, .) – never a comma – is used as the decimal marker ($6.57, not $6,57).
• For the grouping of digits (e.g. £1,234,567) see § Grouping of digits, above.
• Do not place a currency symbol after the accompanying numeric figures (e.g. 123$, 123£, 123€) unless that is the normal convention for that symbol when writing in English: smaller British coins include 1p, 2p, and 5p denominations.
• Currency abbreviations preceding a numeric value are unspaced if they consist of a nonalphabetic symbol alone (£123 or €123), or end with a nonalphabetic symbol (R$123); but spaced (using {{nbsp}}) if completely alphabetic (R 123 or JOD 123).
• Ranges should be expressed giving the currency signifier just once: $250–300, not $250–$300.
• million and billion should be spelled out on first use, and (optionally) abbreviated M or bn (both unspaced) thereafter: She received £70 million and her son £10M; the school's share was $250–300 million, and the charity's $400–450M.
• In general, a currency symbol should be accompanied by a numeric amount e.g. not He converted his US$ to A$ but He converted his US dollars to Australian dollars or He exchanged the US$100 note for Australian dollars.
  • Exceptions may occur in tables and infoboxes where space is limited e.g. Currencies accepted: US$, SFr, £, €. It may be appropriate to wikilink such uses, or add an explanatory note.

Currency conversions

• Conversions of lesser-known currencies may be provided in terms of more familiar currencies – such as the US dollar, euro or pound sterling – using an appropriate rate (which is often not the current exchange rate). Conversions should be in parentheses after the original currency, along with the convert-to year; e.g. the grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000 as of 2009^[update])
• For obsolete currencies, provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. euros for amounts denominated in francs), or a US-dollar equivalent where there is no modern equivalent.
• In some cases, it may be appropriate to provide a conversion accounting for inflation or deflation over time. See {{Inflation}} and {{Inflation-fn}}.
• When converting among currencies or inflating/deflating, it is rarely appropriate to give the converted amount to more than three significant figures; typically, only two significant figures are justified: the grant in 2001 was 10,000,000 Swedish kronor ($1.4M, €970,000, or £850,000), not ($1,390,570, €971,673 or £848,646)

Common mathematical symbols

Shortcuts

• MOS:COMMONMATH
• MOS:MINUS

• The Insert menu below the editing window gives a more complete list of math symbols, and allows symbols to be inserted without the HTML encoding (e.g. ÷) shown here.
• Spaces are placed to left and right when a symbol is used with two operands (the sum 4 + 5), but no space is used when there is one operand (the value +5). Exception: spaces are usually omitted in inline fractions formed with /: 3/4 not 3 / 4.
• The {{mvar}} (for single-letter variables) and {{math}} (for more complicated expressions) templates are available to display mathematical formulas in a manner distinct from surrounding text.
• The {{nbsp}} and {{nowrap}} templates may be used to prevent awkward linebreaks.

Geographical coordinates

Shortcuts

• MOS:COORDS
• MOS:COORDINATES

For draft guidance on, and examples of, coordinates for linear features, see Wikipedia:WikiProject Geographical coordinates/Linear.

Quick guide:

Quick how-to

• v
• t
• e

To add 57°18′22″N 4°27′32″W / 57.30611°N 4.45889°W / 57.30611; -4.45889 to the top of an article, use {{Coord}}, thus:

{{Coord|57|18|22|N|4|27|32|W|display=title}}

These coordinates are in degrees, minutes, and seconds of arc.

"title" means that the coordinates will be displayed next to the article's title at the top of the page (in desktop view only; title coordinates do not display in mobile view) and before any other text or images. It also records the coordinates as the primary location of the page's subject in Wikipedia's geosearch API.

To add 44°06′45″N 87°54′47″W / 44.1124°N 87.9130°W / 44.1124; -87.9130 to the top of an article, use either

{{Coord|44.1124|N|87.9130|W|display=title}}

(which does not require minutes or seconds but does require the user to specify north/ south and east/west) or

{{Coord|44.1124|-87.9130|display=title}}

(in which the north and east are presumed by positive values while the south and west are negative ones). These coordinates are in decimal degrees.

• Degrees, minutes and seconds, when used, must each be separated by a pipe ("|").
• Map datum must be WGS84 if possible (except for off-Earth bodies).
• Avoid excessive precision (0.0001° is <11 m, 1″ is <31 m).
• Maintain consistency of decimal places or minutes/seconds between latitude and longitude.
• Latitude (N/S) must appear before longitude (E/W).

Optional coordinate parameters follow the longitude and are separated by an underscore ("_"):

• dim: dim:N (viewing diameter in metres)
• region: region:R (ISO 3166-1 alpha-2 or ISO 3166-2 code)
• type: type:T (landmark or city(30,000), for example)

Other optional parameters are separated by a pipe ("|"):

• display

  |display=inline (the default) to display in the body of the article only,

  |display=title to display at the top of the article only (in desktop view only; title coordinates do not display in mobile view), or

  |display=inline,title to display in both places.

• name

  name=X to label the place on maps (default is PAGENAME)

Thus: {{Coord|44.1172|-87.9135|dim:30_region:US-WI_type:event

|display=inline,title|name=accident site}}

Use |display=title (or |display=inline,title) once per article, for the subject of the article, where appropriate.

• Per WP:ORDER, the template is placed at the bottom of the article in the 'end matter', after any navigation templates, but before all categories, including the {{DEFAULTSORT}} template. This template may also be placed within an infobox, instead of at the bottom of the article.
• For full details, refer to {{Coord/doc}}.
• Additional guidance is available at obtaining coordinates and converting coordinates.

Geographical coordinates on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically.

First, obtain the coordinates. Avoid excessive precision.

The {{Coord}} template offers users a choice of display format through user styles, emits a Geo microformat, and is recognised (in the title position) by the "nearby" feature of Wikipedia's mobile apps and by external service providers such as Google Maps and Google Earth, and Yahoo. Infoboxes automatically emit {{Coord}}.

The following formats are available.

• For degrees only (including decimal values): {{coord|dd|N/S|dd|E/W}}
• For degrees/minutes: {{coord|dd|mm|N/S|dd|mm|E/W}}
• For degrees/minutes/seconds: {{coord|dd|mm|ss|N/S|dd|mm|ss|E/W}}

where:

• dd, mm, ss are the degrees, minutes and seconds, respectively;
• N/S is either N for northern or S for southern latitudes;
• E/W is either E for eastern or W for western longitudes;
• negative values may be used in lieu of S and W to denote Southern and Western Hemispheres

For example:

For the city of Oslo, located at 59° 54′ 50″ N, 10° 45′ 8″ E:

{{coord|59|54|50|N|10|45|08|E}} – which becomes 59°54′50″N 10°45′08″E / 59.91389°N 10.75222°E / 59.91389; 10.75222

For a country, like Botswana, with no source on an exact geographic center, less precision is appropriate due to uncertainty:

{{coord|22|S|24|E}} – which becomes 22°S 24°E / 22°S 24°E / -22; 24

Higher levels of precision are obtained by using seconds:

{{coord|33|56|24|N|118|24|00|W}} – which becomes 33°56′24″N 118°24′00″W / 33.94000°N 118.40000°W / 33.94000; -118.40000

Coordinates can be entered as decimal values:

{{coord|33.94|S|118.40|W}} – which becomes 33°56′S 118°24′W / 33.94°S 118.40°W / -33.94; -118.40

Increasing or decreasing the number of decimal places controls the precision. Trailing zeros may be added as needed to give both values the same appearance.

Heathrow Airport, Amsterdam, Jan Mayen and Mount Baker are examples of articles that contain geographical coordinates.

Generally, the larger the object being mapped, the less precise the coordinates should be. For example, if just giving the location of a city, precision greater than degrees (°), minutes (′), seconds (″) is not needed, which suffice to locate, for example, the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10 meters or even one meter in some cases (1″ ~15 m to 30 m, 0.0001° ~5.6 m to 10 m).

The final field, following the E/W, is available for attributes such as type:, region:, or scale: (the codes are documented at Template:Coord/doc § Coordinate parameters).

When adding coordinates, please remove the {{coord missing}} tag from the article, if present (often at the top or bottom).

For more information, see the geographical coordinates WikiProject.

Templates other than {{coord}} should use the following variable names for coordinates: lat_d, lat_m, lat_s, lat_NS, long_d, long_m, long_s, long_EW.

See also

• Wikipedia:Date formattings
• m:Help:Date formatting feature at Meta
• m:Help:Calculation § Displaying numbers and numeric expressions at Meta

Notes

1. See Arbitration Committee statements of principles in cases on style-related edit warring in June 2005, November 2005, and February 2006; and Wikipedia:General sanctions/Units in the United Kingdom.
2. See also this July 2022 RfC.
3. For use in tables, infoboxes, references, etc. Only certain citation styles use abbreviated date formats. By default, Wikipedia does not abbreviate dates. Use a consistent citation style within any one article.
4. All-numeric yyyy-mm-dd dates might be assumed to follow the ISO 8601 standard, which mandates the Gregorian calendar. Also, technically all years must have (only) four digits, but Wikipedia is unlikely to need to format a date beyond the year 9999 anytime soon.
5. The routine linking of dates is deprecated. This change was made August 24, 2008, on the basis of this archived discussion. It was ratified in two December 2008 RfCs: Wikipedia:Manual of Style/Dates and numbers/Three proposals for change to MOSNUM and Wikipedia:Manual of Style/Dates and numbers/Date Linking RFC.
6. For consensus discussion on abbreviated date formats like "Sep 2", see Wikipedia talk:Manual of Style/Archive 151 § RFC: Month abbreviations
7. These formats cannot, in general, be distinguished on sight, because there are usages in which 03-04-2007 represents March 4, and other usages in which it represents April 3. In contrast, there is no common usage in which 2007-04-03 represents anything other than April 3.
8. Body in this context means the main prose of the article, as distinguished from reference citations, tabular data, infoboxes, navigation templates, and metadata such as hatnote templates, etc. Other parts of the Manual of Style may use body to mean 'the bulk of the article after the lead section', but that is not the meaning here. Wikipedia's article leads are not written in a different prose style from the material following them.
9. The calendar practices of Oxford Dictionary of National Biography and Encyclopædia Britannica can be inferred by looking up the birth and death dates of famous, well-documented individuals.
10. A change from a preference for two digits, to a preference for four digits, on the right side of year–year ranges was implemented in July 2016 per this RFC.
11. Some precomposed fractions may not work with screen readers, and not all fractions are available precomposed.
12. These three characters are in ISO/IEC 8859-1 and work in screen readers.
13. The number in parentheses in a construction like 1.604(48) × 10⁻⁴ J is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.^[3]
14. The prefixes 0x for hexadecimal and 0b for binary have widespread support in systems programming languages including C, C++, Rust and Swift.
15. One such situation is with Unicode codepoints, which use U+; U+26A7, not 0x26A7.
16. If there is disagreement about the primary units used in a UK-related article, discuss the matter on the article talk-page or at Wikipedia talk:Manual of Style/Dates and numbers (WT:MOSNUM). If consensus cannot be reached, refer to historically stable versions of the article and retain the units used in these as the primary units. Also note the style guides of British publications (e.g. The Times, under "Metric").
17. These definitions are consistent with all units of measure mentioned in the SI Brochure^[4] and with all units of measure catalogued in EU directive 80/181/EEC.^[5]
18. Wikipedia follows common practice regarding bytes and other data traditionally quantified using binary prefixes (e.g. mega- and kilo-, meaning 2²⁰ and 2¹⁰ respectively) and their unit symbols (e.g. MB and KB) for RAM and decimal prefixes for most other uses. Despite the IEC's 1998 international standard creating several new binary prefixes (e.g. mebi-, kibi-, etc.) to distinguish the meaning of the decimal SI prefixes (e.g. mega- and kilo-, meaning 10⁶ and 10³ respectively) from the binary ones, and the subsequent incorporation of these IEC prefixes into the IEC 80000-13, consensus on Wikipedia in computing-related contexts favours the retention of the more familiar but ambiguous units KB, MB, GB, TB, PB, EB, etc. over use of unambiguous IEC binary prefixes. For detailed discussion, see WT:Manual of Style (dates and numbers)/Archive/Complete rewrite of Units of Measurements (June 2008).
19. Whether 00A3 is displayed with one or two bars is typeface (font) dependent.
20. See also this February 2023 RfC.

References

1. Garraty, John A.; Carnes, Mark C., eds. (1999). "Editorial note". American National Biography. Oxford University Press. pp. xxi–xxii.
2. Coordinated Universal Time (UTC) (PDF). Bureau International des Poids et Mesures. June 2, 2009. p. 3. CCTF/09-32. Retrieved October 5, 2022. This coordination began on January 1, 1960, and the resulting time scale began to be called informally 'Coordinated Universal Time.' 
3. "Fundamental Physical Constants: Standard Uncertainty and Relative Standard Uncertainty". The NIST Reference on Constants, Units, and Uncertainty. US National Institute of Standards and Technology. June 25, 2015. Retrieved December 12, 2017.
4. "Chapter 4: Non-SI units that are accepted for use with the SI". SI Brochure: The International System of Units (SI) (PDF) (9th ed.). Bureau International des Poids et Mesures. 2019. Retrieved 2020-09-24. Table 8, p 145, gives additional guidance on non-SI units.
5. "Council Directive of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement". Eur-Lex.Europa.eu. European Union. 2017 [1979]. 80/181/EEC (Document 01980L0181-20090527). Retrieved December 12, 2017.
6. Wilkins, G. A. (1989). "5.14 Time and angle". IAU Style Manual (PDF). International Astronomical Union. p. S23. Retrieved 12 December 2017.