IANA tz database · zone identifier

Pacific/Tongatapu

The IANA tz database identifier for Tonga Standard Time in Tonga. Store this string — not the abbreviation, not the offset — and your timestamps stay correct forever.

UTC+13:00Abbreviation +13No daylight saving
Time in Pacific/Tongatapu☀ Daylight
12:03:35
Thursday, October 15, 2026
Offset
UTC+13:00
Abbreviation
+13
DST
No DST

Current offset

UTC+13:00

same year-round

Abbreviation

+13

tzdb uses numeric abbreviations here

DST behaviour

None

one offset all year

Country

🇹🇴 Tonga

ISO 3166: TO · view country page →

Using this identifier

The string to put in your code.

Pacific/Tongatapu is the identifier to use in code and config for this region. Every modern language, database, and OS resolves it through the same tz database, so the examples here behave identically everywhere.

Avoid storing +13 or +13:00 — abbreviations are ambiguous and fixed offsets can't follow rule changes.

// format a date in this zone
new Intl.DateTimeFormat('en-US', {
timeZone: 'Pacific/Tongatapu',
dateStyle: 'full', timeStyle: 'long'
}).format(new Date());

Offset & DST behaviour

One offset,
9 years.

Pacific/Tongatapu has kept UTC+13:00 year-round since 15 January 2017 — no daylight saving and no offset changes on record since. It is among the most stable identifiers in the database.

Every offset this zone has kept

−11:40:48UTC+13:00 · UNCHANGED 15 January 2017 NOW

Keeping this offset since

15 January 2017

Next transition

None scheduled

no DST rules exist for this zone

Safe to assume

Local = UTC + 13h, always

…but store the identifier anyway

Technical record

The database entry, in full.

source: IANA tz database · release 2026d

IdentifierPacific/Tongatapu
ISO country codeTO🇹🇴 Tonga
Reference coordinates21.13°S, 175.20°Wtz database reference point
Standard offsetUTC+13:00abbreviation +13
Daylight offset—no daylight saving time
tzdb release2026ddata current as of this IANA release

Where it applies

All of Tonga, one clock.

Looking for travel-friendly info? See Nuku'alofa or Tonga Standard Time.

🇹🇴
Tonga

108K people, one time zone. The whole country resolves to Pacific/Tongatapu.

Country page →
🇹🇴 Nuku'alofa
12:03
12:03:35 · +13
pop. 23KTST

Related identifiers

Nearby in the database.

Same offset · UTC+13:00

other zones keeping this offset right now

Frequently asked questions

Answers specific to this identifier — generated from the database record. Can't find what you need? Email [email protected].

What UTC offset is Pacific/Tongatapu?
Pacific/Tongatapu is UTC+13:00, year-round. The offset never changes because the zone does not observe daylight saving time.
Does Pacific/Tongatapu observe daylight saving time?
No. Pacific/Tongatapu stays on UTC+13:00 all year, as it has since 15 January 2017.
Which country uses Pacific/Tongatapu?
Tonga. The identifier covers the whole country.
Is Pacific/Tongatapu the same as TST?
Pacific/Tongatapu is one of the IANA zones that keeps Tonga Standard Time (TST). Use Pacific/Tongatapu in software — TST is a human-friendly label, not a valid identifier.

Free · Developer API

This zone, as JSON.

Its live offset, abbreviation and DST status, plus its coordinates and country, from one endpoint.

GET /v1/timezones Live

Also in the API: time zones by coordinates, conversions that flag daylight saving gaps, and abbreviations decoded.

Get your free API key → All endpoints Plans and pricing

Moving off WorldTimeAPI? Our drop-in replacement needs no key.

// this identifier, resolved live
GET /v1/timezones/Pacific/Tongatapu
{
"data": {
"iana": "Pacific/Tongatapu",
"observes_dst": false,
"country": { "code": "TO", "name": "Tonga" },
"current": {
"utc_offset": "+13:00",
"abbreviation": "+13",
…
},
…
}
}