GMT to MST Time Converter
MST is 7 hours behind GMT. The UK and Ireland are currently on BST (UTC+1:00), and The US Mountain states are currently on MDT (UTC-6:00).
Best Time to Call Between GMT and MST
Both zones are inside normal business hours between 4:00 PM and 5:00 PM GMT — that's 9:00 AM to 10:00 AM MST. That's a 1-hour window.
both at work GMT only MST only neither — hours along the strip are GMT.
Common Times Converted
GMT on the left, MST on the right.
GMT to MST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| GMT | MST | Working hours |
|---|---|---|
| 12:00 AM | 5:00 PM prev day | — |
| 1:00 AM | 6:00 PM prev day | — |
| 2:00 AM | 7:00 PM prev day | — |
| 3:00 AM | 8:00 PM prev day | — |
| 4:00 AM | 9:00 PM prev day | — |
| 5:00 AM | 10:00 PM prev day | — |
| 6:00 AM | 11:00 PM prev day | — |
| 7:00 AM | 12:00 AM | — |
| 8:00 AM | 1:00 AM | — |
| 9:00 AM | 2:00 AM | GMT only |
| 10:00 AM | 3:00 AM | GMT only |
| 11:00 AM | 4:00 AM | GMT only |
| 12:00 PM | 5:00 AM | GMT only |
| 1:00 PM | 6:00 AM | GMT only |
| 2:00 PM | 7:00 AM | GMT only |
| 3:00 PM | 8:00 AM | GMT only |
| 4:00 PM | 9:00 AM | Both zones |
| 5:00 PM | 10:00 AM | MST only |
| 6:00 PM | 11:00 AM | MST only |
| 7:00 PM | 12:00 PM | MST only |
| 8:00 PM | 1:00 PM | MST only |
| 9:00 PM | 2:00 PM | MST only |
| 10:00 PM | 3:00 PM | MST only |
| 11:00 PM | 4:00 PM | MST only |
What GMT and MST Actually Are
GMT — Greenwich Mean Time
The UK and Ireland in winter, plus Iceland, Portugal and much of West Africa. Standing at UTC as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, October 25, 2026, to GMT. Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.
Britain ran an experiment from 1968 to 1971 on permanent UTC+1, abandoning GMT entirely. It was scrapped after complaints about dark winter mornings in Scotland.
MST — Mountain Standard Time
Denver, Salt Lake City, Calgary — and Phoenix year-round. Standing at UTC-7:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, November 1, 2026, to MST. Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.
Arizona has stayed on MST year-round since 1968 — the Navajo Nation within it does observe daylight saving, making the state a patchwork.
What This Means in Practice
Both sides change clocks, on different dates
Both regions observe daylight saving but do not switch on the same day, so for a week or two each spring and fall the gap between them is an hour different from the rest of the year. Those short windows are where recurring invitations quietly break.
Major Cities in Each Zone
Cities on GMT
Cities on MST
Frequently Asked Questions
What is the time difference between GMT and MST?
MST is 7 hours behind GMT.
What is 9:00 AM GMT in MST?
9:00 AM GMT is 2:00 AM MST.
What are the best hours to schedule a call between GMT and MST?
Between 4:00 PM and 5:00 PM GMT, which is 9:00 AM to 10:00 AM MST. Both sides are inside normal business hours through that window.
Does the difference between GMT and MST change during the year?
Yes. Both regions observe daylight saving, and they do not switch on the same dates, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, October 25, 2026.
Does GMT always mean Greenwich Mean Time?
Often used loosely as a synonym for UTC. They differ by less than a second, so for scheduling they are interchangeable.
Does MST always mean Mountain Standard Time?
Arizona stays on MST all year, so Phoenix and Denver are an hour apart for eight months and identical for four.