--:--:--
—
Denver · Phoenix · Salt Lake City
Need overlap across regions? Open the time date meeting planner.
Difference
AST vs MST
UTC → UTC
--:--:--
—
San Juan · Barbados · Halifax (winter)
MST to AST converter
Convert MST to AST time now
Free MST to AST converter. See Mountain Standard Time and Atlantic Standard Time side by side. Live clocks, a 3 hours gap, meeting hours, and a full-day chart for Denver and San Juan.
America/Denver
—
MST → AST
To · Atlantic Standard Time
—
America/Puerto_Rico
Interactive diagram
Watch MST convert into AST
Drag the Mountain hour. Watch the Atlantic clock change.
Mountain
9:00 AM MST
—
AST ← MST
Atlantic
—
Full-day chart
MST to AST hourly conversion chart
Full-day table. Tap a row to copy. Labels follow daylight saving.
| Mountain | Atlantic | UTC offsets |
|---|
Meeting times
Best MST to AST meeting window
Find hours that work on both sides. Then save the slot to your calendar.
Follow along
Step-by-step MST to AST conversion
Four short steps to convert any MST time to AST.
Choose MST time
Select any hour in Mountain Standard Time. Smart mode uses America/Denver.
MST to AST conversion guide
MST to AST conversion guide
This MST to AST converter shows Atlantic Standard Time (UTC−4) for any Mountain Standard Time (UTC−7) time. Use it to schedule between Denver and San Juan. Choose Smart DST for live city clocks. Choose Fixed mode when you only want the MST and AST labels.
Mountain
MST
UTC−7
Denver · Phoenix · Salt Lake City
MST vs AST—
Atlantic
AST
UTC−4
San Juan · Barbados · Halifax (winter)
What is MST to AST conversion?
MST to AST conversion turns a MST clock into the matching AST time. Use it for calls, travel, and teams in Denver and San Juan.
MST to AST time difference
AST is 3 hours ahead of MST. Add 3 hours to the MST time to get AST. The live clocks at the top show the current MST to AST gap.
MST vs AST
MST is UTC−7. AST is UTC−4. They are different names. If a region uses daylight saving, check the live labels.
MST to AST now / current time
Need mst to ast right now? Read the live clocks, or tap Use current time for an instant MST → AST result.
MST to AST time difference
Season / context — tap to explore
See how daylight saving can change this pair.
Mountain—
—MST → AST
Atlantic—
Quick answers
Mountain
Mountain Standard Time (MST)
UTC−7
Mountain Standard Time (MST) is UTC−7. Smart DST uses the city clock America/Denver so daylight saving stays correct for Denver · Phoenix · Salt Lake City.
- Cities: Denver · Phoenix · Salt Lake City
- City clock: America/Denver
- Fixed MST: UTC−7
- On this page it pairs with AST (UTC−4)
Atlantic
Atlantic Standard Time (AST)
UTC−4
Atlantic Standard Time (AST) is UTC−4. Smart DST uses America/Puerto_Rico for cities such as San Juan · Barbados · Halifax (winter).
- Cities: San Juan · Barbados · Halifax (winter)
- City clock: America/Puerto_Rico
- Fixed AST: UTC−4
- From MST: AST is 3 hours ahead of MST
MST to AST FAQ