Convert AST to MST — Time Difference Between Atlantic Standard Time and Mountain Standard Time

How to Convert AST to MST

Drag the slider on the AST timeline to pick your time — the MST time updates instantly. You can also click the time display to type a specific hour or pick one from the 15-minute interval dropdown, and use the date picker to check a different day.

What Is the Time Difference Between AST and MST?

Mountain Standard Time (MST) is 3 hours behind Atlantic Standard Time (AST). To convert, subtract 3 hours — for example, 9:00 AM AST is 6:00 AM MST.

AST to MST Quick Reference

AST to MST Meeting Planner

Use the color-coded table above to find overlapping work hours between Halifax and Denver. Amber rows mark daytime hours — pick a slot that falls in amber on both sides for a meeting that works for everyone.

Why Trust This AST to MST Converter?

Timezoney uses the IANA Time Zone Database — the same source that powers your phone and computer — so every conversion handles daylight saving transitions and half-hour offsets automatically.