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—
San Juan · Barbados · Halifax (winter)
Find the best shared slot in the business meeting planner.
Difference
MST vs AST
UTC → UTC
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Denver · Phoenix · Salt Lake City
AST to MST converter
AST to MST Converter
Convert AST (San Juan) to MST (Denver) now. Live clocks, the current time difference, and a simple meeting window — free.
America/Puerto_Rico
—
AST → MST
To · Mountain Standard Time
—
America/Denver
Interactive diagram
Watch AST convert into MST
Drag the Atlantic hour. Watch the Mountain clock change.
Atlantic
9:00 AM AST
—
MST ← AST
Mountain
—
Full-day chart
AST to MST hourly conversion chart
Full-day table. Tap a row to copy. Labels follow daylight saving.
| Atlantic | Mountain | UTC offsets |
|---|
Meeting times
Best AST to MST meeting window
Find hours that work on both sides. Then save the slot to your calendar.
Follow along
Step-by-step AST to MST conversion
Four short steps to convert any AST time to MST.
Choose AST time
Select any hour in Atlantic Standard Time. Smart mode uses America/Puerto_Rico.
AST to MST conversion guide
AST to MST conversion guide
This AST to MST converter shows Mountain Standard Time (UTC−7) for any Atlantic Standard Time (UTC−4) time. Use it to schedule between San Juan and Denver. Choose Smart DST for live city clocks. Choose Fixed mode when you only want the AST and MST labels.
Atlantic
AST
UTC−4
San Juan · Barbados · Halifax (winter)
AST vs MST—
Mountain
MST
UTC−7
Denver · Phoenix · Salt Lake City
What is AST to MST conversion?
AST to MST conversion turns a AST clock into the matching MST time. Use it for calls, travel, and teams in San Juan and Denver.
AST to MST time difference
MST is 3 hours behind AST. Subtract 3 hours from the AST time to get MST. The live clocks at the top show the current AST to MST gap.
AST vs MST
AST is UTC−4. MST is UTC−7. They are different names. If a region uses daylight saving, check the live labels.
AST to MST now / current time
Need ast to mst right now? Read the live clocks, or tap Use current time for an instant AST → MST result.
AST to MST time difference
Season / context — tap to explore
See how daylight saving can change this pair.
Atlantic—
—AST → MST
Mountain—
Quick answers
Atlantic
Atlantic Standard Time (AST)
UTC−4
Atlantic Standard Time (AST) is UTC−4. Smart DST uses the city clock America/Puerto_Rico so daylight saving stays correct for San Juan · Barbados · Halifax (winter).
- Cities: San Juan · Barbados · Halifax (winter)
- City clock: America/Puerto_Rico
- Fixed AST: UTC−4
- On this page it pairs with MST (UTC−7)
Mountain
Mountain Standard Time (MST)
UTC−7
Mountain Standard Time (MST) is UTC−7. Smart DST uses America/Denver for cities such as Denver · Phoenix · Salt Lake City.
- Cities: Denver · Phoenix · Salt Lake City
- City clock: America/Denver
- Fixed MST: UTC−7
- From AST: MST is 3 hours behind AST
AST to MST FAQ
Common AST to MST questions
What is the AST to MST time difference?
MST is 3 hours behind AST. Fixed labels: AST = UTC−4, MST = UTC−7. Subtract 3 hours from the AST time to get MST.
How do I convert AST to MST quickly?
Subtract 3 hours from the AST time to get MST. Example: 3:00 AM AST → 12:00 AM MST. Or use the live AST to MST converter above.
Is MST the same as AST?
No. AST is UTC−4 (San Juan · Barbados · Halifax (winter)). MST is UTC−7 (Denver · Phoenix · Salt Lake City).
What is a good AST to MST meeting time?
These zones are close. A 10:00 AM AST start is about 7:00 AM MST. That is usually a good call time. Use the meeting planner on this page to export an ICS or Google Calendar invite.
What cities use AST and MST?
AST is common in San Juan · Barbados · Halifax (winter). MST is common in Denver · Phoenix · Salt Lake City. Smart DST uses America/Puerto_Rico and America/Denver.