
ISO Date Format
There are many formats used to represent dates throughout the world.
- In the U.S. the MM/DD/YY format is commonly used.
- Most of Europe uses DD/MM/YY when expressing the date using numbers. When using words, the date would be written in Spain as 2 de enero de 2019 (expressed as January 2, 2019 in U.S. English)
- Japan uses YY/MM/DD or 2019 January 2. (Note the lack of commas or periods in the date.)
These inconsistencies are growing more confusing with the growth of international travel, trade and internet communication.
The international format was defined by ISO, the International Organization for Standardization in their document ISO 8601:2004. This document was created in 2004 to address the inconsistencies in how the date is expressed throughout the world.
ISO 8601:2004 expresses the calendar date using the year, month and day of the month - in that order. Specifically the ISO date format is YYYY-MM-DD:
- YYYY is the year (uses all the digits, i.e. 2019)
- MM is the month (i.e. 01 for January)
- DD is the day of the month (i.e. 02)
For example, "2nd of January 2019" in this ISO format would be written as 2019-01-02.
This ISO document does not solve all international confusion. For example, how does a native German speaker interpret 04/10/09 on a screen they are reading in U.S. English on a German website.