MST Offsets to Every Time Zone

The fixed winter offset: UTC-7

Seven hours behind Coordinated Universal Time. That is the number for the winter half of the Mountain zone, written -07:00 in ISO 8601.

From November to March, most of the US and Canadian portion runs on this offset. Arizona does not switch. Phoenix, Tucson, Mesa and the rest of the state stay on UTC-7 in January and again in July, while Denver moves to UTC-6.

The summer offset: UTC-6

Clocks spring forward on the second Sunday of March at 02:00 local. They fall back on the first Sunday of November at 02:00 local. During that stretch the offset becomes UTC-6, written -06:00.

Recent switch dates:

On 15 July 2026, with the summer offset active, the gaps to major world cities are:

• New York: 2 hours ahead
• Los Angeles: 1 hour behind
• London: 7 hours ahead
• Paris: 8 hours ahead
• Dubai: 10 hours ahead
• Mumbai: 11.5 hours ahead
• Singapore: 14 hours ahead
• Tokyo: 15 hours ahead
• Sydney: 16 hours ahead
• Johannesburg: 8 hours ahead
• São Paulo: 3 hours ahead
• Chicago: 1 hour ahead

Compare with 15 January 2026, when the winter offset was in force: Dubai sat 11 hours ahead, Mumbai 12.5, Tokyo 16, Sydney 18. The shift comes from summer time kicking in on different dates across the hemispheres.

What other time zones share the MST abbreviation?

"MST" is overloaded. Three different offsets hide behind those three letters.

• Mountain Standard Time (North America): UTC-7.
• Malaysian Standard Time: UTC+8. Used across Malaysia.
• Moscow Standard Time: UTC+3. Russia's western zone.

A timestamp labelled "MST" with no location is ambiguous. Check the source or use an IANA identifier instead.

Which IANA zones use the MST offset?

The canonical IANA zone for the Mountain region is America/Denver. It handles the switch between the winter and summer offset automatically. Other zones following the same rules include America/Boise, America/Edmonton, America/Cambridge_Bay, and America/Inuvik.

Two zones work differently:

• America/Phoenix: Arizona, no summer shift, always UTC-7.
• America/Ciudad_Juarez: follows US summer rules to stay aligned with El Paso, Texas.

Major cities on these zones:

Offset vs time zone

An offset is a number: UTC-7, UTC-6, UTC+8. A time zone is a rulebook. It bundles the offset with summer transition dates and historical changes.

• North American MST has offset UTC-7 and switches to UTC-6 in summer.
• Malaysian MST has offset UTC+8 and never switches.
• Moscow MST has offset UTC+3 and never switches.

Knowing only the offset tells you nothing about the zone. Knowing only the abbreviation tells you nothing about the offset. For precise work, reach for an IANA identifier: America/Denver, Asia/Kuala_Lumpur, Europe/Moscow.

Is MST always UTC-7?

No. Only North American Mountain Standard Time sits at UTC-7. Malaysian Standard Time uses UTC+8. Moscow Standard Time uses UTC+3.

What separates MST from MDT?

MST is the winter offset at UTC-7. MDT is the summer offset at UTC-6. The zone toggles between them twice a year.

Does Arizona run on MST or MDT?

MST, all year. It never switches to the summer offset. In summer, Arizona clocks read the same as Pacific Daylight Time (also UTC-7), but the zone name stays Mountain Standard Time.

How do I write the offset in ISO 8601?

North American MST: -07:00. MDT: -06:00. Malaysian Standard Time: +08:00.

Which IANA zone covers Denver?

America/Denver. It is the canonical zone for Denver and most of the Mountain region.

What are the MST time zone offsets for other cities?

For a full list of cities and their IANA zones, see the cities directory. Scheduling across zones? The MST to other time zones page has the offsets.