ChST — Chamorro Standard Time

How to Convert ChST to Other Time Zones

1. Open the ChST converter page: Go to https://www.xconvert.com/time-converter/chst-time-zone to load a visual comparison grid with Chamorro Standard Time (ChST) already shown on a 24-hour timeline. This page is useful when you are planning a call with colleagues in Guam or Saipan, coordinating military, tourism, logistics, or airline-related schedules across the western Pacific, or checking whether business hours in the Northern Mariana Islands overlap with offices in Asia, Australia, or the US mainland.

2. Add comparison cities: Click “+ Add City” and search for cities such as Tokyo, Sydney, and Honolulu to compare ChST with major regional business and travel hubs. Tokyo is relevant for trade and shipping links with Guam, Sydney helps with Australia-Pacific coordination, and Honolulu is a common comparison for US government, defense, and airline operations because it is far behind ChST on the clock despite being another Pacific location.

3. Select a time range on the grid: Click “Select” if needed, then drag across the ChST row to highlight a working window such as 9:00 AM to 11:00 AM ChST. That selection shows immediately in the other rows, letting you see that 9:00 AM in Guam is 8:00 AM in Tokyo, 11:00 AM in Sydney during Australian Eastern Standard Time, and 1:00 PM on the previous day in Honolulu, which is critical when deciding whether a morning meeting in Dededo or Saipan is practical for teams elsewhere.

4. Export or share the result: After selecting a time range, use the export options for ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. This is especially helpful when sending a confirmed meeting slot to a distributed team, sharing a tourism operations briefing across Guam and Japan, or creating a calendar event so each participant sees the meeting automatically in their own local time zone.

About Chamorro Standard Time (ChST)

Chamorro Standard Time (ChST) is the standard time zone used in Guam and the Northern Mariana Islands, two US territories in the western Pacific Ocean. Its exact offset is UTC+10:00, meaning local time in ChST is 10 hours ahead of Coordinated Universal Time (UTC) and 10 hours ahead of GMT as a pure offset comparison.

ChST is used year-round in populated places including Dededo Village, Yigo Village, Tamuning, Tamuning-Tumon-Harmon Village, Mangilao Village, Saipan, and San Jose Village. Guam has a population of roughly 170,000, while the Northern Mariana Islands have a population of about 47,000-50,000, so this time zone matters for government services, tourism, military activity, port operations, schools, and regional business across the Mariana Islands.

Because ChST is UTC+10, it shares the same numeric offset as several other abbreviations at certain times of year, including AEST, AET, CHUT, DDUT, K, PGT, VLAT, YAKST, and YAPT, but those abbreviations do not all refer to the same place or the same daylight saving rules. For example, AEST is commonly used in eastern Australia during standard time, while ChST specifically refers to the Mariana Islands, so travelers and remote teams should match the city or region, not just the offset.

In practical scheduling terms, ChST is 1 hour ahead of Japan Standard Time (UTC+9), 2 hours behind New Zealand Standard Time (UTC+12), and 15 hours ahead of US Eastern Standard Time (UTC-5) or 14 hours ahead of US Eastern Daylight Time (UTC-4). That means when it is 9:00 AM in Guam, it is 8:00 AM in Tokyo, 11:00 AM in Auckland during NZST, and 6:00 PM or 7:00 PM on the previous day in New York depending on the US season.

ChST and Daylight Saving Time

Chamorro Standard Time does not observe Daylight Saving Time. There is no switch to a summer time abbreviation, no seasonal clock change, and the offset remains UTC+10:00 all year in both Guam and the Northern Mariana Islands.

For the current year, 2026, ChST has no DST start date and no DST end date. The clocks in Guam, Saipan, and other Mariana Islands communities do not move forward in spring or back in autumn, which makes ChST easier to use for fixed schedules in aviation support, government coordination, hotel operations, and remote work planning.

The main complication comes from the fact that other regions you compare against ChST may change their clocks seasonally. For example, New York shifts to daylight saving time on March 8, 2026 and returns to standard time on November 1, 2026, while Sydney begins daylight saving time on October 4, 2026 and ends it on April 5, 2026, so the time difference between ChST and those cities changes even though ChST itself does not.

Frequently Asked Questions

What does ChST stand for?

ChST stands for Chamorro Standard Time. The name refers to the Chamorro people, the Indigenous people of Guam and the Mariana Islands, and it is the official standard time used in Guam and the Northern Mariana Islands.

Is ChST the same as GMT?

ChST is not the same time as GMT. GMT is UTC+0, while ChST is UTC+10, so ChST is 10 hours ahead of GMT; for example, when it is 12:00 noon in London on GMT, it is 10:00 PM in Guam.

Which cities use ChST?

Cities and communities using ChST include Dededo Village, Yigo Village, Tamuning, Tamuning-Tumon-Harmon Village, Mangilao Village, Saipan, and San Jose Village. In practice, all of Guam and the Northern Mariana Islands follow the same year-round time, which is important for local government offices, hotels, schools, ports, and airport operations.

What is the UTC offset for ChST?

The UTC offset for ChST is UTC+10:00. This means you add 10 hours to UTC to get local time in Guam or Saipan, so 3:00 AM UTC becomes 1:00 PM ChST on the same calendar day.

When does ChST change?

ChST does not change seasonally because it does not observe daylight saving time. There is no annual switch date, no alternate summer abbreviation, and no clock adjustment in 2026 or in normal yearly practice for Guam and the Northern Mariana Islands.

Is ChST the same as AEST?

ChST and AEST can share the same UTC+10:00 offset during parts of the year, but they are not the same time zone label and they apply to different regions. This matters because eastern Australia may move to daylight saving time in some states, while ChST stays fixed all year, so a meeting that matches perfectly in July may be off by an hour in December.

Which countries or territories use ChST?

ChST is used in the US territories of Guam and the Northern Mariana Islands. Although these are not sovereign countries, they are distinct inhabited territories in the western Pacific, and ChST is the local civil time for their principal population centers and transport hubs.

How far ahead is ChST from UTC and the United States?

ChST is 10 hours ahead of UTC. Compared with the continental United States, it is typically 15 hours ahead of Eastern Standard Time, 14 hours ahead of Eastern Daylight Time, 18 hours ahead of Pacific Standard Time, and 17 hours ahead of Pacific Daylight Time, which is why meetings between Guam and the US mainland often fall in the evening for one side and morning for the other.

Why is ChST useful for travel and business planning?

ChST is important for scheduling flights, hotel operations, military coordination, and regional business across the Pacific because Guam and Saipan are major hubs for tourism and strategic transport. If you are arranging a call between Tamuning and Tokyo, or planning an arrival connection from Honolulu or Manila, knowing that ChST stays fixed at UTC+10 helps avoid mistakes caused by daylight saving changes elsewhere.