ISO 8601

standards for dates, times and (recurring) time intervals

ISO 8601 is an international standard to describe dates and times in the easiest way possible for computers to understand.[2]

Date and time according to ISO 8601 [refresh]
Date and time in UTC2022-10-05T02:17:41+00:00
Date with week number2022-W40-3
Date without year--10-05[1]
Ordinal date2022-278

This standard is based on putting the biggest types of numbers first and the smallest numbers last. Because years are bigger than months, and months are bigger than days, they are put in the order of YEAR-MONTH-DAY.

A basic ISO date for today looks like 2022-10-05.

The basic ISO time is 02:17.

Another very important principle is that when a computer or human puts ISO 8601 dates into alphabetical order, they are also in chronological order.

People can also use these dates, but it is currently not common for people in any country to write dates using this standard in their day-to-day lives, tho many Asian countries follow YEAR-MONTH-DAY order.


  1. last in ISO8601:2000, in use by "RFC 6350 - vCard Format Specification". IETF. August 2011. Retrieved 2016-06-29. Truncated representation, as specified in [ISO.8601.2000], Sections d), e), and f), is permitted.
  2. ISO, FAQ: Numeric representation of Dates and Time