IANA tz database · zone identifier

America/Phoenix

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

UTC-07:00Abbreviation MSTNo daylight saving
Time in America/Phoenix☀ Daylight
15:59:57
Wednesday, October 14, 2026
Offset
UTC-07:00
Abbreviation
MST
DST
No DST

Current offset

UTC-07:00

same year-round

Abbreviation

MST

used year-round

DST behaviour

None

one offset all year

Country

🇺🇸 United States

ISO 3166: US · view country page →

Using this identifier

The string to put in your code.

America/Phoenix 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 MST or -07:00 — abbreviations are ambiguous and fixed offsets can't follow rule changes.

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

Offset & DST behaviour

One offset,
58 years.

America/Phoenix has kept UTC-07:00 year-round since 29 October 1967 — 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

−07:28:18UTC-07:00 · UNCHANGED 29 October 1967 NOW

Keeping this offset since

29 October 1967

Next transition

None scheduled

no DST rules exist for this zone

Safe to assume

Local = UTC − 7h, always

…but store the identifier anyway

Technical record

The database entry, in full.

source: IANA tz database · release 2026d

IdentifierAmerica/Phoenix
ISO country codeUS🇺🇸 United States
Reference coordinates33.45°N, 112.07°Wtz database reference point
Standard offsetUTC-07:00abbreviation MST
Daylight offset—no daylight saving time
tzdb release2026ddata current as of this IANA release

Where it applies

One of United States's 29 zones.

Looking for travel-friendly info? See Phoenix or Mountain Standard Time.

🇺🇸
United States

340M people, 29 time zones — this identifier covers one of them.

Country page →
🇺🇸 Phoenix
15:59
15:59:57 · MST
pop. 1.6MMST
🇺🇸 Tucson
15:59
15:59:57 · MST
pop. 543KMST

Related identifiers

Nearby in the database.

Same zone group · Mountain Standard Time

other identifiers keeping MST

Same offset · UTC-07:00

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 America/Phoenix?
America/Phoenix is UTC-07:00, year-round. The offset never changes because the zone does not observe daylight saving time.
Does America/Phoenix observe daylight saving time?
No. America/Phoenix stays on UTC-07:00 all year, as it has since 29 October 1967.
Which country uses America/Phoenix?
United States. It is one of 29 IANA zones covering the country.
Is America/Phoenix the same as MST?
America/Phoenix is one of the IANA zones that keeps Mountain Standard Time (MST). Use America/Phoenix in software — MST 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/America/Phoenix
{
"data": {
"iana": "America/Phoenix",
"observes_dst": false,
"country": { "code": "US", "name": "United States" },
"current": {
"utc_offset": "-07:00",
"abbreviation": "MST",
…
},
…
}
}