Use international date format (ISO)

How does one write a date on the Web? There are so many formats available, most of them incompatible with others, that it can be a usability nightmare to choose a date representation when writing for an international, cross-cultural audience, as is the case on the web. Fortunately, there is one solution in the ISO-developed international date format.

The date interpretation quagmire

The worst potential usability problems come when the date is written only with numbers as in the following example, because the date's interpretation will be different from one country to another.

Imagine the following date: 02/04/03

Which does it mean?

2nd of April 2003 (European style)

4th of February 2003 (USA style)

3rd of April 2002

Your answer will depend, mostly, on which country you live in.

In most cases, writing the date in full letters would be better than the example above. Apr. 3rd, 2002 , for example will be easy to understand for any English-speaking audience.

But this system does not cross borders much better than its numerical counterparts: does the french 12 Août 2042 actually mean something for a Japanese person? Or when you notice a 昭和44年03月16日 in Japanese which is 16 March 1969 in English.

The ISO date format

The international format defined by ISO (ISO 8601) tries to address all these problems by defining a numerical date system as follows: YYYY - MM - DD where

YYYY is the year [all the digits, i.e. 2012]

is the year [all the digits, i.e. 2012] MM is the month [01 (January) to 12 (December)]

is the month [01 (January) to 12 (December)] DD is the day [01 to 31]

For example, "3rd of April 2002", in this international format is written: 2002-04-03 .

Note that this format can also be used to represent precise date and time, with timezone information

Using numerical dates does have also some pitfalls with regard to readability and usability, as explained in the Date formats FAQ . Albeit not perfect, ISO date format is, however, the best choice for a date representation that is universally (and accurately) understandable.

Further Reading

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