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 DST — never observed
Time in America/Phoenix☀ Daylight
15:56:40
Wednesday, July 15, 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

Never

has never observed daylight saving

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

IdentifierAmerica/Phoenix
ISO country codeUS🇺🇸 United States
Reference coordinates33.45°N, 112.07°Wtz database reference point
Standard offsetUTC-07:00abbreviation MST
Daylight offset—daylight saving has never been observed

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
15:56
15:56:40 · MST
pop. 1.6MMST
🇺🇸 Tucson
15:56
15:56:40 · 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 has never observed DST — it has kept UTC-07:00 continuously 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.

Everything on this page — offset, abbreviation, DST rules, coordinates — from one endpoint, always current with the latest tzdb release.

GET /v1/timezones Live

countries, cities, convert, DST transitions coming next.

Get your free API key →
// this identifier, resolved live
GET /v1/timezones?iana=America/Phoenix
{
"iana": "America/Phoenix",
"utc_offset": "-07:00",
"abbreviation": "MST",
"observes_dst": false,
"country": "US"
}