MST to AST Time — Convert Mountain Standard Time (US) to Atlantic Standard Time

AST is currently 3 hours ahead of MST.

MST is Mountain Standard Time (UTC−7). Most of the US Mountain zone switches to MDT (UTC−6) in summer, but Arizona (except the Navajo Nation) stays on MST year-round.

On Clockjumper, AST refers to Atlantic Standard Time in Atlantic Canada and the Caribbean (UTC−4). The same letters are also used for Arabia Standard Time (UTC+3) — check the city or UTC offset to be sure which is meant.

The MST → AST offset stays constant across the year — neither zone shifts for daylight saving in a way that changes this gap.

Is AST ahead of or behind MST right now?

AST is currently 3 hours ahead of MST.

What is the current MST to AST time difference?

Right now the gap is 3 hours — AST is 3 hours ahead of MST.

Does the MST → AST offset change during the year?

No. Neither Mountain Standard Time (US) nor Atlantic Standard Time shifts for daylight saving in a way that changes this offset — the gap is the same all year.

Does MST observe daylight saving time?

MST is itself the standard-time form. Mountain Standard Time (US) is in force at UTC-7 through the winter months; outside that window the same zone is on MDT (UTC-6).

Does AST observe daylight saving time?

AST is itself the standard-time form. Atlantic Standard Time is in force at UTC-4 through the winter months; outside that window the same zone is on ADT (UTC-3).

What time is 3 AM MST in AST?

3:00 AM MST is 6:00 AM AST.

What time is 8 AM MST in AST?

8:00 AM MST is 11:00 AM AST.

What time is 9 AM MST in AST?

9:00 AM MST is 12:00 PM AST.

What time is 10 AM MST in AST?

10:00 AM MST is 1:00 PM AST.

What time is 11 AM MST in AST?

11:00 AM MST is 2:00 PM AST.

What time is 12 PM (noon) MST in AST?

12:00 PM MST is 3:00 PM AST.

What time is 2 PM MST in AST?

2:00 PM MST is 5:00 PM AST.

What time is 3 PM MST in AST?

3:00 PM MST is 6:00 PM AST.

What time is 4 PM MST in AST?

4:00 PM MST is 7:00 PM AST.

What time is 5 PM MST in AST?

5:00 PM MST is 8:00 PM AST.

What time is 9 PM MST in AST?

9:00 PM MST is 12:00 AM (next day) AST.

What time is 10 PM MST in AST?

10:00 PM MST is 1:00 AM (next day) AST.

When is the best time to schedule a call between MST and AST?

The working-hours overlap (09:00–17:00 in both zones) runs roughly 9:00 AM – 2:00 PM MST (≈ 5 hours). The midpoint of that window — 11:30 AM MST, 2:30 PM AST — is the safest single slot to propose for a live call.

What time zone does MST refer to?

MST refers to Mountain Standard Time (US) (IANA: America/Denver).

What time zone does AST refer to?

AST refers to Atlantic Standard Time (IANA: America/Halifax).

Is MST on this page the same as other zones that share the letters "MST"?

MST is Mountain Standard Time (UTC−7). Most of the US Mountain zone switches to MDT (UTC−6) in summer, but Arizona (except the Navajo Nation) stays on MST year-round.

Is AST on this page the same as other zones that share the letters "AST"?

On Clockjumper, AST refers to Atlantic Standard Time in Atlantic Canada and the Caribbean (UTC−4). The same letters are also used for Arabia Standard Time (UTC+3) — check the city or UTC offset to be sure which is meant.

• AST to MST
• AEST to MST
• AST to CST
• BST to MST
• AST to EST
• CDT to MST
• AST to GMT
• CET to MST
• AST to IST
• CST to MST
• AST to PST
• EDT to MST
• CST to AST
• EST to MST
• EST to AST

• About MST (Mountain Standard Time (US)) →
• About AST (Atlantic Standard Time) →
• All timezone conversion pages →
• Explore workday-overlap research →