What standard time is used in Guam and the Northern Mariana Islands?

Chamorro Standard Time is the standard time used in Guam and the Northern Mariana Islands.

Chamorro Standard Time, abbreviated ChST, is UTC+10:00. It covers the U.S. territory of Guam and the Commonwealth of the Northern Mariana Islands, including Saipan. Neither territory observes daylight saving time, so the same standard-time offset applies throughout the year.

The time zone was formerly called the Guam Time Zone. The name Chamorro reflects the Indigenous Chamorro people of the Mariana Islands. The U.S. Congress formally created Chamorro Standard Time in federal law on December 23, 2000, replacing the older Guam-centered terminology in federal usage.

It is easy to confuse ChST with Wake Island Time or Hawaii-Aleutian Time. Wake Island is two hours ahead, at UTC+12:00, while Hawaii-Aleutian Standard Time is generally UTC−10:00. ChST also matches Queensland’s standard clock time because Queensland does not use daylight saving time.