UTC−12:00 is an identifier for a time offset from UTC of −12:00. It is the offset of the time zone that is the last to celebrate a New Year, sometimes referred to as the International Date Line West time zone (IDLW).[1]

World map with the time zone highlighted
UTC offset
Current time
20:39, 19 December 2019 UTC−12:00 [refresh]
Central meridian
180 degrees
Date-time group

As standard time (all year round)


UTC−12:00 is a nautical time zone comprising the high seas between 180° and 172°30′W longitude, and the time is obtained by subtracting twelve hours from Coordinated Universal Time. Ships using this time are the last to begin each calendar day.

Characteristics of the time zone that observes UTC−12:00

A number of inhabited islands lie within the longitudinal limits of this time zone, but none of them keeps the date and time of UTC−12:00. Instead, they keep the time and date (or just the date) of one of the neighbouring zones, usually because they belong, politically, to an island group whose other members lie mostly in the neighbouring time zone.

Since the International Date Line West (IDLW) time zone represents the last place on Earth where a particular date exists before rolling over to the next date, it is sometimes used for deadlines and referred to as Anywhere on Earth (AoE). This means that if the deadline has not passed in the UTC–12:00 zone, the deadline has not yet passed.[1]

The IDLW is also used in software testing for timezone related code that uses system default time zone because in some cases they may be the same as on the developer's computer who running the test. Since there are not any inhabitants and programmers or data centers which are performing the tests then the tests are always protected from such cases.

See also


  1. "IEEE 802.16 AOE Deadline Documentation". IEEE 802 LAN/MAN Standards Committee. Retrieved 1 January 2018.
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