11 Numbers and dates
11.5 Date forms
Figures are used for days and years in dates. Use cardinal numbers not ordinal numbers for dates:
12 August 1960
2 November 2003
Do not use the endings -st, -rd, or -th in conjunction with a figure, as in 12th August 1960, unless copying another source: dates in letters or other documents quoted verbatim must be as in the original. Where less than the full date is given, write 10 January (in notes 10 Jan.), but the 10th. If only the month is given it should be spelled out, even in notes. An incomplete reference may be given in ordinal form:
In British English style dates should be shown in the order day, month, year, without internal punctuation: 2 November 2003. In US style the order is month, day, year: November 2, 2003.
A named day preceding a date is separated by a comma: Tuesday, 2 November 1993; note that when this style is adopted a terminal second comma is required if the date is worked into a sentence:
There is no comma between month and year: in June 1831. Four-figure dates have no comma—2001—although longer dates do: 10,000 bc.
Abbreviated all-figure forms are not appropriate in running text, although they may be used in notes and references. The British all-figure form is 2/11/03 or 2.11.03 (or the year may be given in full). In US style the all-figure form for a date, which is always separated by slashes rather than full points, can create confusion in transatlantic communication, since 11/2/03 is 2 November to an American reader and 11 February to a British one. Note that the terrorist attacks of 11 September 2001 are known by the shorthand September 11 or 9/11 not only in the US but also in Britain and around the world.
The dating system promoted by the ISO is year, month, day, with the elements separated by hyphens: 2003-11-02. This style is preferred in Japan and increasingly popular in technical, computing, and financial contexts. Another alternative, common on the Continent and elsewhere, is to use (normally lower-case) Roman numerals for the months (2. xi. 03). This system serves to clarify which number is the day and which the month in all contexts—a useful expedient when translating truncated dates into British or US English.
For precise dates in astronomical work, use days (d), hours (h), minutes (m), and seconds (s) (2001 January 1d 2h 34m 4.8s) or fractions of days (2001 January 1.107). See also
For abbreviations of days and months see