IANA tz database · zone identifier

America/Boise

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-06:00Abbreviation MDTObserves daylight saving

Time in America/Boise☀ Daylight

16:58:21

Wednesday, July 15, 2026

Offset

UTC-06:00

Abbreviation

MDT

DST

Active

Current offset

UTC-06:00

standard UTC-07:00 · daylight UTC-06:00

Abbreviation

MDT

the daylight-saving form

DST behaviour

Observes

changes clocks twice a year

Country

🇺🇸 United States

ISO 3166: US · view country page →

Using this identifier

The string to put in your code.

America/Boise 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 MDT or -06:00 — abbreviations are ambiguous and fixed offsets can't follow rule changes.

// format a date in this zone

new Intl.DateTimeFormat('en-US', {

timeZone: 'America/Boise',

dateStyle: 'full', timeStyle: 'long'

}).format(new Date());

Offset & DST behaviour

Two offsets,
every year.

America/Boise alternates between MST (UTC-07:00) and MDT (UTC-06:00). Right now it is on MDT; clocks fall back on 1 November 2026.

The year at a glance

Technical record

The database entry, in full.

source: IANA tz database

IdentifierAmerica/Boise

ISO country codeUS🇺🇸 United States

Reference coordinates43.61°N, 116.20°Wtz database reference point

Standard offsetUTC-07:00abbreviation MST

Daylight offsetUTC-06:00abbreviation MDT

Where it applies

One of United States's 29 zones.

🇺🇸

United States

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

Country page →

Related identifiers

Nearby in the database.

Same zone group · Mountain Standard Time

other identifiers keeping MST

America/Cambridge_BayCanada America/Ciudad_JuarezMexico America/CrestonCanada America/Dawson_CreekCanada America/DenverUnited States America/EdmontonCanada America/Fort_NelsonCanada America/InuvikCanada America/PhoenixUnited States

Same offset · UTC-06:00

other zones keeping this offset right now

America/BelizeBelize · Central Standard Time America/ChihuahuaMexico · Central Standard Time America/Costa_RicaCosta Rica · Central Standard Time America/El_SalvadorEl Salvador · Central Standard Time America/GuatemalaGuatemala · Central Standard Time America/ManaguaNicaragua · Central Standard Time

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/Boise?: America/Boise is currently UTC-06:00 (MDT). It alternates between UTC-07:00 in winter and UTC-06:00 in summer.
Does America/Boise observe daylight saving time?: Yes. Clocks fall back at the next transition on 1 November 2026, as they do twice every year.
Which country uses America/Boise?: United States. It is one of 29 IANA zones covering the country.
Is America/Boise the same as MST?: America/Boise is one of the IANA zones that keeps Mountain Standard Time (MST). Use America/Boise 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/Boise

{

"iana": "America/Boise",

"utc_offset": "-06:00",

"abbreviation": "MDT",

"observes_dst": true,

"country": "US"

}