Date and time format - ISO 8601

What is ISO 8601?

ISO 8601 describes an internationally accepted way to represent dates and times using numbers.

When dates are represented with numbers they can be interpreted in different ways. For example, 01/05/12 could mean January 5, 2012, or May 1, 2012. On an individual level this uncertainty can be very frustrating, in a business context it can be very expensive. Organizing meetings and deliveries, writing contracts and buying airplane tickets can be very difficult when the date is unclear.

ISO 8601 tackles this uncertainty by setting out an internationally agreed way to represent dates:


For example, September 27, 2012 is represented as 2012-09-27.

What can ISO 8601 do for me?

ISO 8601 can be used by anyone who wants to use a standardized way of presenting dates and times. It helps cut out the uncertainty and confusion when communicating internationally.

The full standard covers ways to write:

How can I get ISO 8601?

You can buy the full standard from the ISO Store, or from the ISO member in your country.

ISO Store

  • ISO 8601:2004
    Data elements and interchange formats -- Information interchange -- Representation of dates and times

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