TOST — Tonga Summer Time
See what TOST means, when UTC+14 applies in Tonga, and how to compare or convert it with other time zones.
How to Convert TOST to Other Time Zones
Open the TOST converter page: Go to https://www.xconvert.com/time-converter/tost-time-zone to load the visual comparison grid with Tonga Summer Time (TOST, UTC+14) as the reference row. This page is useful when you need to line up work with contacts near the International Date Line, such as shipping partners in the Pacific or remote teammates coordinating with Australia, New Zealand, or the US West Coast.
Add comparison cities: Click + Add City and search for cities that commonly interact with Tonga’s time zone, such as Auckland, Sydney, and Los Angeles. This helps with practical scheduling: Auckland is a key regional business hub, Sydney is relevant for aviation and trade across the South Pacific, and Los Angeles is useful for tourism, logistics, and international calls that cross the date line.
Select a time range on the grid: Click Select if needed, then drag across the TOST row to highlight a meeting window, such as 9:00 AM to 11:00 AM TOST. Because TOST is UTC+14, that same slot appears as 8:00 AM to 10:00 AM in Auckland during NZDT (UTC+13), 6:00 AM to 8:00 AM in Sydney during AEDT (UTC+11), and 11:00 AM to 1:00 PM in Los Angeles on the previous calendar day during PST (UTC-8), which is critical when confirming whether a “Monday morning” meeting in Tonga is still Sunday afternoon in California.
Export and share the result: After selecting the range, use the export options shown by the tool: ICS download, Google Calendar, Gmail, Copy to clipboard, or Share link. For example, if you are arranging a regional operations call across Tonga, New Zealand, and Australia, exporting to Google Calendar or sending the ICS file ensures each participant sees the event in their own local time automatically, reducing date-line mistakes.
About Tonga Summer Time (TOST)
TOST stands for Tonga Summer Time, the daylight saving time used in Tonga when summer clock rules are in effect. Its exact offset is UTC+14:00, which means local time in TOST is 14 hours ahead of Coordinated Universal Time and among the earliest civil times in the world on any given date.
Tonga is a Polynesian island country in the South Pacific, east of Fiji and south of Samoa, and when daylight saving time is active, it uses TOST rather than its standard-time offset. In practical terms, if it is 12:00 noon UTC, it is 2:00 AM the next day in TOST, which is why this time zone often appears a full calendar day ahead of North America.
The abbreviation with the same UTC offset listed here is LINT, or Line Islands Time, which is also UTC+14. Even though the offsets match, they are not interchangeable in every context because LINT is used for a different region of the Pacific, while TOST specifically refers to Tonga’s summer daylight saving period.
Because TOST is so far ahead of UTC, it matters for industries that depend on date-sensitive coordination, including aviation scheduling, maritime logistics, travel booking, and distributed customer support. A business in Tonga can begin its Monday workday while companies in the continental United States are still on Sunday, so using a visual overlap tool is especially helpful for avoiding missed calls and incorrect booking dates.
TOST and Daylight Saving Time
TOST is the daylight saving time version of Tonga’s clock, and it switches from TOT (Tonga Time, UTC+13) to TOST (UTC+14) when daylight saving is observed. That one-hour advance means a local 8:00 AM start in Tonga becomes aligned one hour later relative to UTC, which can slightly improve overlap with New Zealand and other Pacific markets during the southern summer.
For the current year, 2026, Tonga is not currently observing daylight saving time, and there are no active 2026 DST transition dates scheduled for TOST. Tonga suspended daylight saving changes in recent years, so although TOST remains a valid time-zone abbreviation in historical and database usage, travelers and schedulers should verify whether they are dealing with a historical timestamp or current local civil time.
Historically, when Tonga did switch into TOST, clocks moved forward by 1 hour from UTC+13 to UTC+14, and when daylight saving ended, they moved back by 1 hour to standard time. This distinction is important when reviewing older flight itineraries, archived calendar invites, or system logs, because a timestamp marked TOST indicates a different UTC relationship than standard Tonga Time.
If you are scheduling something current in Tonga, the safest approach is to check the selected date in the converter’s date picker and compare it visually against other cities. That is especially useful for events around year-end, when many Pacific jurisdictions have historically changed summer schedules and confusion can arise between standard and daylight abbreviations.
Frequently Asked Questions
What does TOST stand for?
TOST stands for Tonga Summer Time. It is the daylight saving time abbreviation historically used for Tonga when the country advanced its clocks to UTC+14:00 during the southern hemisphere summer period.
Is TOST the same as GMT?
No, TOST is not the same as GMT. GMT is effectively UTC+0, while TOST is UTC+14, so TOST is 14 hours ahead of GMT; when it is 9:00 AM GMT, it is 11:00 PM TOST on the same date, and depending on the comparison zone, often the next calendar day relative to the Americas.
Which cities use TOST?
TOST is associated with Tonga, but there are no major separately listed principal cities in common time-zone references for this abbreviation on this page. In practical use, it applies to locations within Tonga when daylight saving rules are active or when historical timestamps from Tonga’s summer period are being referenced.
What is the UTC offset for TOST?
The UTC offset for TOST is UTC+14:00. That means you add 14 hours to UTC to get Tonga Summer Time, so 6:00 PM UTC becomes 8:00 AM TOST the next day.
When does TOST change?
TOST changes when Tonga moves between standard time (TOT, UTC+13) and summer time (TOST, UTC+14) under daylight saving rules. For 2026, there are no current DST transition dates scheduled, so TOST is mainly relevant for historical records, software time-zone databases, and older calendar entries.
Is TOST currently used in Tonga?
At present, Tonga is not actively observing daylight saving time in 2026, so current local civil time is generally not using TOST. However, the abbreviation still appears in historical data, time-zone libraries, and archived schedules, which is why understanding it remains useful for travel records and timestamp conversion.
Is TOST the same as LINT?
TOST and LINT share the same numeric offset of UTC+14, but they refer to different regions and naming conventions. TOST is tied to Tonga Summer Time, while LINT refers to Line Islands Time, so the local legal time context and place name are different even though the clock offset matches.
Why is TOST important for scheduling international calls?
TOST matters because UTC+14 is one of the most advanced offsets in the world, which creates large date differences with Europe and the Americas. For example, a 10:00 AM TOST meeting can fall on the previous afternoon in Los Angeles or very early morning in parts of North America, so using a side-by-side grid helps confirm both the hour and the correct calendar day.