Looking for an unambiguous calendar-and-clock format that is internationally understood? It’s time for ISO 8601.

This ISO standard helps remove doubts that can result from the various day–date conventions, cultures and time zones that impact a global operation. It gives a way of presenting dates and times that is clearly defined and understandable to both people and machines.

What can ISO 8601 do for me?

When dates are represented with numbers they can be interpreted in different ways. For example, 01/05/22 could mean January 5, 2022, or May 1, 2022. 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:


Therefore, the order of the elements used to express date and time in ISO 8601 is as follows: year, month, day, hour, minutes, seconds, and milliseconds.

For example, September 27, 2022 at 6 p.m. is represented as 2022-09-27 18:00:00.000.

ISO 8601 can be used by anyone who wants to use a standardized way of presenting:

  • Date
  • Time of day
  • Coordinated Universal Time (UTC)
  • Local time with offset to UTC
  • Date and time
  • Time intervals
  • Recurring time intervals
Standardization is a truly international activity, and I’ve been lucky to have worked with more nationalities than I can remember. But, that said, my first business meeting with a German remains etched …

Highlights from our store

  • ISO 8601-1:2019
    Date and time
    Representations for information interchange – Part 1: Basic rules
  • ISO 8601-2:2019
    Date and time
    Representations for information interchange – Part 2: Extensions