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MST to AST: Mountain Time to Atlantic Time

3 hours ahead of MST

AST compared with MST, right now. Swap: AST to MST ⇄

MSTTuesday, November 3, 2026MST · UTC−7ASTTuesday, November 3, 2026AST · UTC−4

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MST to AST conversion table

For Tuesday, November 3, 2026. Rows where both places are inside 9 AM–5 PM are highlighted.

MSTAST
12:00 AM3:00 AM
1:00 AM4:00 AM
2:00 AM5:00 AM
3:00 AM6:00 AM
4:00 AM7:00 AM
5:00 AM8:00 AM
6:00 AM9:00 AM
7:00 AM10:00 AM
8:00 AM11:00 AM
9:00 AM12:00 PM
10:00 AM1:00 PM
11:00 AM2:00 PM
12:00 PM3:00 PM
1:00 PM4:00 PM
2:00 PM5:00 PM
3:00 PM6:00 PM
4:00 PM7:00 PM
5:00 PM8:00 PM
6:00 PM9:00 PM
7:00 PM10:00 PM
8:00 PM11:00 PM
9:00 PM12:00 AM (next day)
10:00 PM1:00 AM (next day)
11:00 PM2:00 AM (next day)

About these time zones

MST: Mountain Standard Time

Mountain Time (MST/MDT). Denver, Salt Lake City, Albuquerque, Boise and Calgary. MST is UTC−7; in summer most of the region uses MDT, UTC−6. Most of Arizona stays on MST all year.

Sunday, March 14, 2027: clocks go forward 1 hour at 2:00 AM local time (UTC−7 → UTC−6).

AST: Atlantic Standard Time

Atlantic Time (AST/ADT). Nova Scotia, New Brunswick and Prince Edward Island (with daylight saving), plus Puerto Rico and much of the Caribbean, which stay on AST (UTC−4) all year.

Sunday, March 14, 2027: clocks go forward 1 hour at 2:00 AM local time (UTC−4 → UTC−3).

Questions about MST and AST time

What is the time difference between MST and AST?

The current difference is shown at the top of this page. MST uses Mountain Standard Time (MST, UTC−7) as standard time and Mountain Daylight Time (MDT, UTC−6) during daylight saving time; AST uses Atlantic Standard Time (AST, UTC−4) as standard time and Atlantic Daylight Time (ADT, UTC−3) during daylight saving time. The difference can change if only one side observes daylight saving time or if their clocks change on different dates. Choose your meeting date in the converter to check the applicable offset.

When it is 9:00 AM in MST, what time is it in AST?

On Tuesday, November 3, 2026, 9:00 AM in MST was 12:00 PM in AST. The conversion table above shows today’s values.

Do the clocks change in MST or AST?

MST: Sunday, March 14, 2027: clocks go forward 1 hour at 2:00 AM local time (UTC−7 → UTC−6). AST: Sunday, March 14, 2027: clocks go forward 1 hour at 2:00 AM local time (UTC−4 → UTC−3).

Is MST the same as MDT?

MST is the standard-time name and MDT the daylight-saving name for Mountain Time. People often say MST all year; this converter uses the time actually in effect on the date you choose.

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