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Help:Manual of Style (dates and numbers)

MyWikiBiz, Author Your Legacy — Monday October 23, 2017
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This Manual of Style, like all style guides, attempts to encourage consistency and ease of reading. The guidelines here are just that: guidelines are not inflexible rules; one way is often as good as another, but if everyone does it the same way, MyWikiBiz will be easier to read, write and edit.

New contributors are reminded that clear, informative and unbiased writing is always more important than presentation and formatting. (See Help:Editing policy.)


Years, decades, and centuries

This section describes how to link to years, decades and centuries. See sections which follow, regarding when such linking is appropriate.

See Anno Domini for a discussion on what is meant by AD and BC notation, and Common Era for a discussion on what is meant by CE and BCE notation.

A page title that is just a positive whole number is always a year. Pages also exist for days of the year, decades, centuries and even millennia. The formats for references to years are:

Articles for the year 500 BC and earlier should be redirected to the relevant decade. Articles for the year 1700 BC and earlier should be redirected to the relevant century. Articles for the year 4000 BC and earlier should be redirected to the relevant millennium.

Note that the first century BC was from 100 BC to 1 BC (there was no year 0) so 1700 BC would be the first year of the 17th century BC, 1800 BC would be the first year of the 18th century BC, etc. Similarly, 4000 BC was the first year of the fourth millennium BC, not the last year of the fifth millennium BC.

When only an approximate date is available the abbreviation "c." (Latin: circa, "about") may be used; see the example at Rameses III below. When a date is uncertain—because the sources are unreliable—that fact should be noted and, if possible, the source specified. For example, "according to Livy, the Roman Republic was founded in 509 BC", or "The Mahabharata is traditionally said to have been composed in 1316 BCE".

Dates containing a month and a day

If a date includes both a month and a day, then the date should almost always be linked to allow readers' date preferences to work, displaying the reader's chosen format. The day and the month should be linked together, and the year should be linked separately if present. For example:

To create a date that is linked but not converted, use a piped link with alternate text, for example "[[17 February|17 February]]". This should only be done with good reason, such as in a direct quotation. In this case, it may be preferable not to link the date at all, as the link does not then help with readers' date preferences.

In article titles, dates will not be converted.

There are some exceptions to the rule that dates with a month and a day should always be linked:

  • Within a quotation, the date should appear to all readers as it did in the source of the quotation.

Partial dates

If the date does not contain both a month and a day, date preferences do not apply: linking or not linking the date will make no difference to the text that the reader sees. So when considering whether such a date should be linked or not, editors should take into account the usual considerations about links, including the recommendations of Help:Only make links that are relevant to the context.

There is consensus among editors that bare month and day names should not be linked unless there is a specific reason that the link will help the reader to understand the article. There is less agreement about links to years. Some editors believe that links to years are generally useful to establish context for the article. Others believe that links to years are rarely useful to the reader and reduce the readability of the text. Another possibility is to link to a more specific article about that year, for example [[2006 in sports|2006]], although some people find this unintuitive because the link leads to an unexpected destination.

Examples of links which do not respond to readers' date preferences:

  • Year only: [[1974]]1974.
  • Month only: [[April]]April. Generally should not be linked.
  • Century: [[20th century]]20th century.
  • Decade: [[1970s]]1970s.
  • Year and month: [[April]] [[1974]]April 1974.
  • Recent year and month: [[April 2000]]April 2000. Currently articles only exist for combinations from the year 1999 to the present.
  • Day of the week (with or without other date elements): [[Tuesday]]Tuesday. Generally should not be linked.

Yearless dates

Articles addressing recent events often omit the year, under the impression that "June 2" clearly refers to the recent past. However, as time goes on, the context will be lost; therefore the first use of a date should include the year. Once the year is clearly established, yearless dates can be used judiciously in nearby prose. See also Help:As of and Category:Current events.

Date formats related to topics

If the topic itself concerns a specific country, editors may choose to use the date format used in that country. This is useful even if the dates are linked, because new users and users without a MyWikiBiz account do not have any date preferences set, and so they see whatever format was typed. See Help:Manual of Style#National varieties of English for more guidance.

ISO date formats

ISO 8601 dates, for example 1958-02-17, are unambiguous. However, they are not common in English prose, and are therefore unfamiliar to many readers. Accordingly, they should generally not be used in normal prose. This applies even if they are in a link: although the software will convert such dates according to users' date preferences (for example, [[1958-02-17]]1958-02-17), new users and unregistered users do not have any date preferences set, and will therefore see the unconverted ISO 8601 date.

This advice only applies to dates in normal prose. ISO 8601 dates may sometimes be useful elsewhere; for example, they are useful in lists, tables, for dates of birth/death, for conciseness and ease of comparison.

Incorrect date formats

  • Do not use numbers to express a month, except in ISO 8601 format. Always express a month as a whole word (e.g. "February" not "2"). Do not use abbreviations like "Feb" unless the available space is extremely limited, such as in a table, infobox, or the like.
  • Do not use two digits to express a year unless at the end of a range, e.g., "1970–87" (the same for BC). In all other cases, use four digits for years and decades after AD 999 (the same for BC). Using the less formal two-digit form for a decade is acceptable when not ambiguous; for example, when referring to the decade of the 20th century known as "the eighties", use "1980s" or, less often, "the '80s", not just "80s".
  • Use consistent date formatting throughout an article, unless there is a good reason to vary it.
  • Do not use ordinal suffixes:
    • Incorrect: "February 14th" and "14th February"
    • Correct: "February 14" and "14 February"
  • Do not use articles:
    • Incorrect: "the 14th of February"
    • Correct: "February 14" and "14 February"
  • Do not put a comma or the word "of" between a month and year:
    • Incorrect: "December, 1945" and "December of 1945"
    • Correct: "December 1945"
  • Do not use an apostrophe to indicate a decade:
    • Incorrect: 1970's
    • Correct: 1970s

Direct quotations

An important exception to these guidelines is that direct quotations—the word-for-word reproduction of a written or oral text—should not be altered to conform to the MyWikiBiz "Manual of Style". In other words, a paragraph such as this (fictional) quotation from a newspaper report is fine as is:

"Tony Blair, responding to critics in his party, said 'The world has totally changed since the 11th of September.' He was echoing earlier sentiments by Lord Ronald McDonald, who said that 'nine-eleven' was the day that the American public woke up to the reality of terrorism."

Dates of birth and death

  • Charles Darwin (12 February 180919 April 1882)
    • Locations should be included in the biography portion of the body article. For example, "(12 February 1809 in Shrewsbury, Shropshire, England–19 April 1882 in Downe, Kent, England)" should be separated to "(12 February 180919 April 1882) … He was born in Shrewsbury, Shropshire, England … He died in Downe, Kent, England".
  • Socrates (470399 BC) (or "BCE")
    • When only the years are known.
  • Serena Williams (born September 26 1981)
    • For a person still living at the time the article was written.
    • Notice that the form is not "(September 26 1981–)"
  • Offa (died 26 July 796)
    • When the date of birth is unknown.
  • Genghis Khan (c.1162August 18, 1227)
    • When the date of birth is known approximately.
  • Dionysius Exiguus (c.470–c.540)
    • When dates of birth and death are known approximately.
  • Robert Menli Lyon (born 1789, date of death unknown)
    • When the date of death is unknown, but the person is certainly now dead.
  • Rameses III (reigned c.1180 BCE–c.1150 BCE)
    • When only the dates of the reign are known and only approximately.
  • Osmund (fl. 760–772)
    • When the person was known to have been alive (flourishing) at certain dates. Note that [[floruit|fl.]] is used to link to floruit, in case the meaning is not familiar.
  • Aethelwalh (fl. c.660–685)
    • Here the person was known to have been alive approximately as early as 660, and to have died in 685.

Note the preferred use of "c." rather than "circa", "ca." or a question mark.

Ranges of dates are given with a spaced or unspaced hyphen or en dash (–). See Help:Manual of Style (dashes).


Because the seasons are reversed in each hemisphere—while areas near the equator tend to have just wet and dry seasons—neutral wording should be used to describe times of the year, such as "in early 1990", "in the second quarter of 2003", "around September" or an exact date, rather than references to seasons, unless there is some particular need to do so (e.g., "the autumn harvest"). It is ambiguous to say that Apollo 11 landed on the Moon in the summer of 1969—whose summer? However, quoted references to seasons should not be changed.


  • Both the BCE/CE era names and the BC/AD era names are acceptable, but should be consistent within an article.
  • Normally you should use plain numbers for years in the Anno Domini/Common Era, but when events span the start of the Anno Domini/Common Era, use AD or CE for the date at the end of the range (note that AD precedes the date and CE follows it). For example, [[1 BC]]–[[1|AD 1]] or [[1 BCE]]–[[1|1 CE]].
  • In articles about prehistory, if you use BP (before present) or MYA (million years ago), expand these abbreviations when you first use them, as most readers will be unfamiliar with them.
  • When either of two styles are acceptable it is inappropriate for a MyWikiBiz editor to change from one style to another unless there is some substantial reason for the change. For example, with respect to English spelling as opposed to American spelling it would be acceptable to change from American spelling to English spelling if the article concerned an English subject. Revert warring over optional styles is unacceptable; if the article is colour rather than color, it would be wrong to switch simply to change styles as both are acceptable.

Different calendars

You can give dates in any appropriate calendar, as long as you also give the date in either the Julian or Gregorian calendar, as described below. For example, an article on the early history of Islam may give dates in both the Islamic calendar and the Julian calendar.

  • Current events should be given in the Gregorian calendar.
  • Dates before the adoption of the Gregorian calendar on 1582-10-15 should usually be given in the Julian calendar. The Julian day and month should not be converted to the Gregorian calendar, but the start of the Julian year should be taken to be 1 January (see below for more details).
  • Dates of events in countries using the Gregorian calendar should be given in the Gregorian calendar. This includes much of Europe from 1582, the British Empire from 1752-09-14, Russia from 1918-02-14, and so on (see the Gregorian calendar article).

Other dates are ambiguous. Your options for this period are:

  • Give the dates in the Julian calendar only. This means that the dates will match the dates in the primary sources for that period. If you do this you should indicate that the dates are in the Julian calendar.
  • Convert the dates to the Gregorian calendar. This means that events in different countries can be correlated.
  • Give dates in both calendars, for example, William Shakespeare died on 1616-04-23 (Old Style)/1616-05-03 (New Style).

At some places and times, dates other than 1 January were used as the start of the year. The most commonly encountered convention is the Annunciation Style used in Britain and its colonies in which the year started on 25 March. See the New Year article for a list of other styles. You should always convert dates so that they correspond with years starting on 1 January. If it is important to preserve consistency with primary sources, you may give the date in the original style, but then you must also give the date in the modern style. For example, Elizabeth I of England died on 1602-03-24 (Old Style)/1603-03-24 (New Style). Although this would correspond to 3 April 1603 if fully converted into the Gregorian calendar, the month and day of a British event are normally not converted.


Time formatting

Context shall determine whether the 12-hour or 24-hour clock notation should be used. In either case, the colon is used to separate hours, minutes and seconds.

Times in the 12-hour clock end with lower case "a.m." or "p.m." These suffixes generally cannot be omitted, except that "noon" and "midnight" should be used instead of "12 p.m." and "12 a.m." respectively; some readers find the latter ambiguous. Beware that even "12 midnight" does not unambiguously distinguish between midnight at the start and end of a given date.

24-hour clock times have no a.m./p.m./noon/midnight suffix. Discretion may be used to determine if the hour has a leading zero. 00:00 refers to midnight at the start of a day and 12:00 refers to noon. (In addition, 24:00 can be used for midnight at the end of a given date, which can be useful to state the end of a time interval.)


12-hour clock Not 24-hour clock Not
2 p.m. 2pm 14:00 14.00
2:34 p.m. 2.34 PM 14:34 1434
12:04:38 a.m. 12.04 38″ A.M. 00:04:38 or 0:04:38
noon 12 noon 12:00

Time zones

When writing a date, first consider where the event happened and use the time zone there. For example, the date of the Attack on Pearl Harbor should be December 7, 1941 (Hawaii time/date). If it is difficult to judge where, consider what is significant. For example, if a vandal based in Japan attacked a Pentagon computer in the United States, use the time zone for the Pentagon, where attack had its effect.

If you know it, include the UTC date and time of the event in the article, indicating that it is UTC.



Very large numbers may be divided up by commas every three places (e.g.: 2,900,000), starting from the decimal separator in both directions. (This is different from the SI/ISO 31-0 notation style, where punctuation marks are not used, but as an option, a non-breaking thin space may be inserted every three places.) In scientific contexts, scientific notation is preferred. Large round numbers are generally assumed to be approximations; it is necessary to qualify with "about" or a similar term where the statement would otherwise be misleading.

A period (".") must be used as the decimal separator, separating the integer part from the fractional part.

For numbers between minus one and plus one, include the leading 0 ("0.02", not ".02").

The minus sign has two representations. One is the normal hyphen-minus ("-") available on every computer keyboard (twice on those with numeric keypad); the other ("−") is most easily entered as −.


  • The word percent or per cent is commonly used to indicate percentages in the body of an article. The symbol % may be more common in scientific or technical articles, or in complex listings. Be consistent throughout an article.
  • Use the symbol % with a numeral for a percentage in such locations as tables and infoboxes. There is no space between the numeral and the symbol %.

Numbers in words

  • Whole numbers from zero to ten should be spelled out as words in the body of an article. Use numerals in tables and infoboxes.
  • Numbers above ten may be written out if they are expressed in two or fewer words, except in tables and infoboxes. Example: "sixteen", "eighty-four", "two hundred", "twenty million" but "3.75", "544", "21 million".
  • Proper names and formal numerical designations should instead comply with common usage. Example: Chanel No. 5, 4 Main Street, 1-Naphthylamine, channel 6.
  • Within a context or a list, style should be consistent. Example: There were 5 cats, 12 dogs, and 32 birds. or There were five cats, twelve dogs, and thirty-two birds.
  • It is considered awkward for a numeral to be the first word of a sentence: recast the sentence or spell the number out.
  • Fractions standing alone should be spelled out unless they occur in a percentage. If fractions are mixed with whole numbers, use numerals.

Natural number

Natural number has two meanings:

  • positive integer, or
  • non-negative integer (including zero).

When referring to such numbers, explicitly use one of the above phrases rather than "natural numbers", unless it does not matter which interpretation is chosen.


Sometimes numbers and dates are expressed in ranges, such as "14–17" for the numbers 14 to 17. It is often preferable to write this out—for example, "from 14 to 17" or "fourteen through seventeen"—to avoid confusion with "fourteen minus seventeen", which is expressed with spaces, as "14 − 17".

Traditionally, ranges of numbers and dates are given with an en dash (type – or click the – button below the edit window). Therefore, many MyWikiBiz users support using this style exclusively. However, some sources now use spaced or unspaced hyphens, at least online, and some MyWikiBiz users believe that these hyphens should not be changed to en dashes.

See Help:Manual of Style (dashes) for more information.

Non-base-ten notations

For numbers expressed in bases other than base ten:

  • In computer-related articles, use the C programming language prefixes 0x (zero-ex) for hexadecimal and 0 (zero) for octal. For binary, use 0b. It may be a good idea to include a note at the top of the page about these prefixes.
  • In all other articles, use subscript notation. For example: 1379, 2416, 2A912, A87D16 (use <sub> and </sub>).
  • For base eleven and higher, use whatever symbols are conventional for that base. A common convention is to use A–Z for digits ten to thirty-five. Where letters are present, use uppercase: 0x5AB3, not 0x5ab3.

Units of measurement

MyWikiBiz articles are intended for people anywhere in the world. Try to make articles simple to read and translate.

  • Conversions should generally be included and not be removed.
  • The Scientific style section of the Manual of Style states "For units of measure, use SI units as the main units in science articles, unless there are compelling historical or pragmatic reasons not to do so."
  • If editors cannot agree about the sequence of units, put the source value first and the converted value second.
  • If for some reason the choice of units is arbitrary, choose SI units as the main unit, with other units in parentheses. For subjects dealing with the United States, it might be more appropriate to use U.S. measurements first, i.e. mile, foot, U.S. gallon.
  • Spell out units in the text.
  • Use digits and unit symbols for values in parentheses and for measurements in tables. For example, "a pipe 100 millimetres (4 in) in diameter and 16 kilometres (10 mi) long" or "a pipe 4 inches (100 mm) in diameter and 10 miles (16 km) long".
  • Converted values should use a level of precision similar to that of the source value. For example, "the Moon is 380,000 kilometres (240,000 mi) from Earth", not "(236,121 mi)".
  • Use standard abbreviations when using symbols. For example, metre is m, kilogram is kg, inch is in (not " or ″), foot is ft (not ' or ′), and pound is lb (not #).
  • Do not append an s for plurals of unit abbreviations. For example, kg, in, yd, lb, not kgs, ins, yds, lbs.
  • Some non-metric units have more than one version. Be specific. For example, U.S. gallon or imperial gallon rather than just gallon. Similarly, use nautical mile or statute mile rather than just mile in aviation, space, sea and in some other contexts.
  • Put a space between the value and the unit symbol, for example "25 kg" not "25kg". Preferably, use &nbsp; for the space (25&nbsp;kg) so that it does not break lines.
  • Following footnotes or citing sources conventions, add a reference for numbers that identifies not only the source, but also the source's original units.
  • In a direct quotation, if the text includes an obscure use of units (e.g., five million board feet of lumber), annotate it with a footnote which provides metric units rather than changing the actual quotation.

Magnitude prefixes

Binary prefixes

Template:Quantities of bytes In computing, binary prefixes can be used to quantify large numbers where powers of two are more useful than powers of ten. They are commonly written and pronounced identically to the SI prefixes, but each successive prefix is multiplied by 1024 (210) rather than 1000 (103).

Avoiding confusion

Using the prefixes kilo-, mega-, giga-, etc., and symbols like kB, MB, GB, etc., in the binary sense can cause serious confusion. In January 1999, the International Electrotechnical Commission introduced in IEC 60027 the prefixes kibi-, mebi-, gibi-, etc., and the symbols Ki, Mi, Gi, etc. to specify binary multiples of a quantity. They have since been officially adopted by several other organizations such as IEEE and NIST.

The use of the new binary prefix standards in the Wikipedia is not required, but is recommended for use in all articles where binary capacities are used. In articles where the precise byte capacities are important to description, the binary prefix should be used with binary capacities and the SI prefix should be used with decimal capacities (and should be noted as decimal if not immediately clear). If a contributor changes an article's usage from kilo- etc. to kibi- etc. where the units are in fact binary, that change should be accepted. However, because they are less familiar, binary unit prefixes such as MiB should be linked at least once per article to avoid confusion. Link as [[Mebibyte|MiB]] to avoid a disambiguation page.

Do not change all SI prefixes to IEC prefixes in computing contexts, only those that are actually being used in a binary sense. For example, do not change a "160 GB HDD" to "158.69 GiB" (still less "160 GiB"), but you can change 512 MB RAM to 512 MiB RAM where it is important to do so. (Notice that the number does not change because the SI prefix was used in a binary sense. Both usages are acceptable, but the MiB reference is not ambiguous.)

Measures that typically use decimal multiples:

Measures that typically use binary multiples:


  • The highest score recorded for the Deuces High pinball game was 11,933,750.
  • The hippopotamus stands 1.5 metres (5 ft) at the shoulders and weighs between 2,700 and 4,500 kilograms (6,000–9,900 lb).
    • The [[hippopotamus]] stands [[1 E0 m|1.5 metres]] (5&nbsp;ft) at the shoulders and weighs between [[Orders of magnitude (mass)|2,700 and 4,500 kilograms]] (6,000&ndash;9,900&nbsp;lb).
  • … between 2.7 and 4.5 tons.
  • The first sub-four-minute mile was run by Roger Bannister.
  • The 155-millimetre diameter projectile offers a wide range of options for battlefield usage.
  • 10² = 100
    • 10&sup2; = 100
    • 10² = 100
  • A large number such as 156,234,000,000,000,000,000,000,000,000 can be concisely recorded as 1.56234{{e|29}}, and a small number such as 0.0000000000234 can be written as 2.34e−11×10−11.
  • The computer has a 160 GB hard disk and 512 MiB of RAM.

See orders of magnitude and the talk page there for ongoing, possibly resolved debate on which style of exponent notation to use for large numbers.

Geographical coordinates

Geographical coordinates on Earth should be entered using a template. This standardizes the format. It also provides a link to a page with several links to maps of the coordinates, and is part of a new way to handle geographic information in Wikipedia.

Depending on the form of the coordinates, three template formats are available. For just degrees, use d mode:

{{coor d|DD|N/S|DD|E/W|}}

For degrees/minutes, use dm mode:

{{coor dm|DD|MM|N/S|DD|MM|E/W|}}

For degrees/minutes/seconds, use dms mode:

{{coor dms|DD|MM|SS|N/S|DD|MM|SS|E/W|}}


  • DD, MM, SS are the degrees, minutes, seconds listed one by one
  • N/S is either N or S, depending on which hemisphere
  • E/W is either E or W, depending on which hemisphere


For the city of Oslo, located at 59° 55′ N, 10° 44′ E, enter:

{{coor dm|59|55|N|10|44|E|}}

which becomes 59°55′N, 10°44′E

For a country, like Botswana, the d mode is more appropriate:

{{coor d|22|S|24|E|}}

which becomes 22° S 24° E

For higher precision, use the dms mode:

{{coor dms|33|56|24|N|118|24|00|W|}}

which becomes 33°56′24″N, 118°24′00″W

Examples of articles using geographical coordinates:

Decimal degrees, minutes, or seconds

  • degrees can be specified with decimals, in d mode
  • minutes can be specified with decimals, in dm mode
  • seconds can be specified with decimals, in dms mode


{{coor d|12.0433|S|77.0283|W|}}

Which becomes 12.0433° S 77.0283° W


The final field, following the E/W, is available for specification of attributes, such as type, region and scale. For more information, see geographical coordinates.


Due to planned enhancements in functionality, the above template concept is subject to change. As long as the above templates are adhered to, any necessary changes will be performed automatically by a robot.


Competing/overlapping proposals: Help:Manual of Style (dates and numbers)#Currency.

In country-specific articles such as Economy of Australia use only the symbol specific to the country, in this case $, with an italicized note placed at the top of the article to make this clear.

In articles which are not country specific, such as Wealth, use ''[[United States dollar|US$]]100'' or ''one hundred [[United States dollar]]s''. Use the most commonly used English abbreviation, and link to the relevant article only at the first usage. If there is no common English abbreviation or symbol, use the ISO 4217 standards.

In countries where the euro is used, do not place "EU" or similar prefix before the € sign.

When a currency abbreviation is placed in front of a number, those which end in a symbol (such as GB£ or ) should not be separated from the number. Those which end in an alphabetic character (such as RMB) should be separated by a single, non-breaking space (&nbsp;).


Conversions can be made into other currencies that are more familiar to most readers, such as the euro or United States dollar. Conversions should be in parentheses after the original currency, with the year given as a rough point of reference, for example, one thousand Swiss francs (approx. US$763, c.2005), rounding to the nearest whole unit.


Good style

Bad style

  • $123 — This can lead to ambiguity as to which dollar or peso is meant in articles that are not specific to one currency zone.
  • $123 — this is hard to read
  • 123$ — Although it is read aloud like this, this is not a standard way to write it. Dollars are sometimes written this way by Canadian francophones writing in English. This is also the way Portuguese escudos were expressed before the introduction of the euro.
  • $123 (US)
  • $US123

See also