Time zone · Oceania
TST
Tonga Standard Time
Tonga Standard Time is a single-zone region that runs a steady UTC+13:00 year-round, making Tongatapu one of the world’s permanent 'first-to-midnight' places. No daylight-saving changes means teams here enjoy a predictable rhythm that naturally sits ahead of most global calendars.
Saturday, June 6, 2026
Current offset
UTC+13:00
Standard · +13
Daylight saving
Not observed
Year-round standard time
IANA zones
1
None observe daylight saving
DST offset
—
No summer variant
About TST
A fixed, year-round offset.
Tonga Standard Time is a single-zone region that runs a steady UTC+13:00 year-round, making Tongatapu one of the world’s permanent 'first-to-midnight' places. No daylight-saving changes means teams here enjoy a predictable rhythm that naturally sits ahead of most global calendars.
IANA zones · the technical identifiers
The zone that resolve to TST.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Cities currently on TST
The same hour, city by city.
1 city · all UTC+13:00
Where TST is used
One country.
Same offset · UTC+13:00
Other zones at UTC+13:00 right now.
These named zones share TST's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about TST, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Is Tonga Standard Time affected by daylight saving?
- No — Tonga Standard Time never observes daylight saving, so the UTC+13:00 offset stays constant every day of the year.
- Why does Tonga mostly use a single timezone?
- With essentially one inhabited main zone (Tongatapu), Tonga Standard Time represents the whole country through a rare single-zone setup, keeping civil time tightly unified across the nation.
- What’s distinctive about Tonga’s clock?
- UTC+13:00 places Tongatapu among the earliest countries to enter a new calendar day, often ticking over to midnight well ahead of Europe and many parts of the Americas.
- Has Tonga ever flirted with daylight saving?
- While Tongan time has shifted in the past for economic or seasonal reasons, today’s regime is permanently fixed—no DST, no spring-forward surprises.
- How does UTC+13:00 affect business hours?
- Early-morning European or late-evening East Coast calls can overlap nicely with Tonga’s late-morning window, making UTC+13:00 surprisingly handy for Asia–Americas coordination.
- Are there quirks in how Tonga records dates?
- Because Tonga crosses the International Date Line loop early relative to its neighbors, the same moment can fall on different weekdays here than in nearby Pacific islands.
- Is the region code ‘TST’ intuitive?
- Yes — ‘TST’ stands for Tonga Standard Time, matching the abbreviation ‘+13’ used in many local references to its constant UTC+13:00 offset.
- What event cemented the current offset?
- The modern UTC+13:00 regime has been anchored since early 2017, when local adjustments settled into today’s fixed, no-DST arrangement.
- Will that offset ever change?
- No official transitions are scheduled—Tonga Standard Time looks set to remain UTC+13:00 indefinitely, adding stability for long-term scheduling.
Free · Developer API
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