TIP 88

Use international date format (ISO)

There are potential usability problems when you do not use international date format. Dates are expressed with different patterns depending on the country. When the date is written only with numbers, it becomes very difficult to identify the language.

Good practice

To avoid this confusion, there is an international format defined by ISO (IS0 8601): YYYY-MM-DD where

• YYYY is the year
• MM is the month 01 (January) to 12 (December)
• DD is the day 01 to 31

Examples

Let's say that you have a Web page with a date expressed like that: 02/04/03

What is the intended meaning?

• 2nd of April 2003 (European style)
• 4th of February 2003 (USA style)
• 3rd of April 2002

How could a visitor understand which date system has been used? Are the readers of the website able to guess what date format you are using?

The date, in international format is written: 2002-04-03

Note that using numerical dates has also some pitfalls with regard to readability and usability. Accessibility101 is currently re-writing our own datestamp javascript to comply.

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