Convert any time between GST and MST, with a full 24-hour table and the hours when both sides are actually at work.

GST to MST Time Converter

MST is 10 hours behind GST. GST is UTC+4:00, and The US Mountain states are currently on MDT (UTC-6:00).

Worth knowing right now. The US Mountain states are currently on MDT, not MST, because daylight saving is in effect. The 10 hours above is the gap between those two regions today, which is almost certainly what you want. Taken strictly as written, GST to MST is 11 hours.
GST
Gulf Standard Time
06:17:51 PM
Sunday, October 11, 2026
UTC+4:00
-10:00
hours difference
⇆ Reverse
MST
Mountain Standard Time
08:17:51 AM
Sunday, October 11, 2026
UTC-6:00

Best Time to Call Between GST and MST

Standard 9-to-5 hours in these two zones never overlap, so someone has to take the call outside their working day. The most workable window is 5:00 PM to 10:00 PM GST, which is 7:00 AM to 12:00 PM MST.

both at work GST only MST only neither  —  hours along the strip are GST.

GST to MST: Full 24-Hour Conversion Table

Shaded rows are working hours; the darker shade marks the hours when both zones are at work.

GSTMSTWorking hours
12:00 AM 2:00 PM prev day MST only
1:00 AM 3:00 PM prev day MST only
2:00 AM 4:00 PM prev day MST only
3:00 AM 5:00 PM prev day —
4:00 AM 6:00 PM prev day —
5:00 AM 7:00 PM prev day —
6:00 AM 8:00 PM prev day —
7:00 AM 9:00 PM prev day —
8:00 AM 10:00 PM prev day —
9:00 AM 11:00 PM prev day GST only
10:00 AM 12:00 AM GST only
11:00 AM 1:00 AM GST only
12:00 PM 2:00 AM GST only
1:00 PM 3:00 AM GST only
2:00 PM 4:00 AM GST only
3:00 PM 5:00 AM GST only
4:00 PM 6:00 AM GST only
5:00 PM 7:00 AM —
6:00 PM 8:00 AM —
7:00 PM 9:00 AM MST only
8:00 PM 10:00 AM MST only
9:00 PM 11:00 AM MST only
10:00 PM 12:00 PM MST only
11:00 PM 1:00 PM MST only

What GST and MST Actually Are

GST — Gulf Standard Time

Dubai, Abu Dhabi, Sharjah, Muscat. Standing at UTC+4:00 as written, and the region does not change its clocks, so that offset holds all year. GST also refers to South Georgia Time (UTC-2), which you are very unlikely to want.

The Gulf states have never observed daylight saving, so Dubai's offset has been unchanged for decades — unusual stability for a region that grew as fast as it did.

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

The date changes mid-working-day

For 1 of the eight hours in a normal GST working day, the equivalent MST time falls on a different calendar date. Anything scheduled in that stretch needs the date checked as well as the time, or a Tuesday call quietly becomes a Wednesday one at the other end.

This gap is not fixed

MST changes its clocks and GST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, November 1, 2026 unless someone resets it.

Nearly opposite sides of the clock

At 10 hours apart, one side's morning is the other side's night. Handing work over at the end of a shift usually beats trying to get both parties in the same call.

Frequently Asked Questions

What is the time difference between GST and MST?

MST is 10 hours behind GST. That is the live figure. Taken strictly as written, the gap between GST and MST is 11 hours — the two differ because at least one of these regions is currently on daylight saving.

What is 9:00 AM GST in MST?

9:00 AM GST is 11:00 PM the previous day MST.

What are the best hours to schedule a call between GST and MST?

Standard business hours in these two zones do not overlap at all, so one side has to work outside the 9-to-5. The most workable window is 5:00 PM to 10:00 PM GST, which is 7:00 AM to 12:00 PM MST.

Does the difference between GST and MST change during the year?

Yes. MST observes daylight saving and GST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, November 1, 2026.

Does GST always mean Gulf Standard Time?

GST also refers to South Georgia Time (UTC-2), which you are very unlikely to want.

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.

Converting between two time zones regularly? Bookmark this page — the clocks update live and the table follows daylight saving automatically.