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

MST is currently 3 hours behind 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.

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.

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

Is MST ahead of or behind AST right now?

MST is currently 3 hours behind AST.

What is the current AST to MST time difference?

Right now the gap is 3 hours — MST is 3 hours behind AST.

Does the AST → MST offset change during the year?

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

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).

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).

What time is 3 AM AST in MST?

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

What time is 8 AM AST in MST?

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

What time is 9 AM AST in MST?

9:00 AM AST is 6:00 AM MST.

What time is 10 AM AST in MST?

10:00 AM AST is 7:00 AM MST.

What time is 11 AM AST in MST?

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

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

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

What time is 2 PM AST in MST?

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

What time is 3 PM AST in MST?

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

What time is 4 PM AST in MST?

4:00 PM AST is 1:00 PM MST.

What time is 5 PM AST in MST?

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

What time is 9 PM AST in MST?

9:00 PM AST is 6:00 PM MST.

What time is 10 PM AST in MST?

10:00 PM AST is 7:00 PM MST.

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

The working-hours overlap (09:00–17:00 in both zones) runs roughly 12:00 PM – 5:00 PM AST (≈ 5 hours). The midpoint of that window — 2:30 PM AST, 11:30 AM MST — is the safest single slot to propose for a live call.

What time zone does AST refer to?

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

What time zone does MST refer to?

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

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.

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.

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

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