MST to AST Converter
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Selected conversion
The selected date and time will appear here when the converter loads.
MST and AST examples
These examples always use MST (UTC-7) and AST (UTC-4). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
MST is 3 hours behind AST.
How the time difference changes
For most of the year, MDT is 3 hours behind ADT. At other times of the year, MST is 3 hours behind AST. Briefly around clock changes, MDT is 2 hours behind AST or MST is 4 hours behind ADT.
For most of the year, working hours of 9:00 am to 5:00 pm in MDT correspond to 12:00 pm to 8:00 pm in ADT. At other times of the year, working hours of 9:00 am to 5:00 pm in MST correspond to 12:00 pm to 8:00 pm in AST.
Compare MST time with AST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Mountain Standard Time is 3 hours behind Atlantic Standard Time
5:00 am05:00 in MST is 8:00 am08:00 in AST
MST to AST call time
Best time for a conference call or a meeting is between 9am-2pm in MST which corresponds to 12pm-5pm in AST
5:00 am05:00 Mountain Standard Time (MST). Offset UTC -7:00 hours
8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours
5:00 am05:00 MST / 8:00 am08:00 AST
| MST | AST |
|---|---|
| 12am (midnight) | 3am |
| 1am | 4am |
| 2am | 5am |
| 3am | 6am |
| 4am | 7am |
| 5am | 8am |
| 6am | 9am |
| 7am | 10am |
| 8am | 11am |
| 9am | 12pm (noon) |
| 10am | 1pm |
| 11am | 2pm |
| 12pm (noon) | 3pm |
| 1pm | 4pm |
| 2pm | 5pm |
| 3pm | 6pm |
| 4pm | 7pm |
| 5pm | 8pm |
| 6pm | 9pm |
| 7pm | 10pm |
| 8pm | 11pm |
| 9pm | 12am (midnight) |
| 10pm | 1am |
| 11pm | 2am |
| 00:00 | 03:00 |
| 01:00 | 04:00 |
| 02:00 | 05:00 |
| 03:00 | 06:00 |
| 04:00 | 07:00 |
| 05:00 | 08:00 |
| 06:00 | 09:00 |
| 07:00 | 10:00 |
| 08:00 | 11:00 |
| 09:00 | 12:00 |
| 10:00 | 13:00 |
| 11:00 | 14:00 |
| 12:00 | 15:00 |
| 13:00 | 16:00 |
| 14:00 | 17:00 |
| 15:00 | 18:00 |
| 16:00 | 19:00 |
| 17:00 | 20:00 |
| 18:00 | 21:00 |
| 19:00 | 22:00 |
| 20:00 | 23:00 |
| 21:00 | 00:00 |
| 22:00 | 01:00 |
| 23:00 | 02:00 |
Mountain Standard Time
Offset: MST is 7 hours behind Greenwich Mean Time (GMT) and is used in North America
Countries using this time zone: Canada, Mexico, United States
Principal Cities: The largest city in the MST time zone is Phoenix in the United States, with about 1.446 million people. Other major cities in this time zone include Calgary, Edmonton, El Paso, Denver.
French: HNR - Heure Normale des Rocheuses
Spanish: MT - Zona Pacífico
Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Mountain Daylight Time (MDT).
Start: Mountain Standard Time (MST) started on Sunday, November 2, 2025 at 2:00 am local time and clocks were set one hour back to Sunday, November 2, 2025, 1:00 am. Standard time starts annually on the first Sunday of November.
End: Mountain Standard Time (MST) ends on Sunday, March 8, 2026 at 2:00 am local time and clocks are set one hour forward to Sunday, March 8, 2026, 3:00 am local daylight time instead. Standard time ends annually on the second Sunday of March.
MST representations, usage and related time zones
- -07 - basic short
- -0700 - basic
- -07:00 - extended
- -0700 - sign character (-) followed by a four digit time providing hours (07) and minutes (00) of the offset. Indicates an offset of seven hours to the west of the zero meridian.
- Tango - Military abbreviation for MST
- T - short form of 'Tango'
- America/Boise
- America/Cambridge_Bay
- America/Ciudad_Juarez
- America/Creston
- America/Dawson
- America/Dawson_Creek
- America/Denver
- America/Edmonton
- America/Fort_Nelson
- America/Hermosillo
- America/Inuvik
- America/Mazatlan
- America/Phoenix
- America/Shiprock
- America/Whitehorse
- America/Yellowknife
- Canada/Mountain
- Canada/Yukon
- MST
- MST7MDT
- Mexico/BajaSur
- Navajo
- US/Arizona
- US/Mountain
- MST - Mountain Standard Time
- PDT - Pacific Daylight Time
- YST - Yukon Standard Time
- T - Tango Time Zone
Atlantic Standard Time
Offset: AST is 4 hours behind Greenwich Mean Time (GMT) and is used in North America
Countries using this time zone: Antigua & Barbuda, Anguilla, Aruba, Barbados, St Barthelemy, Bermuda, Caribbean NL, Canada, Curaçao, Dominica, Dominican Republic, Grenada, Greenland, Guadeloupe, St Kitts & Nevis, St Lucia, St Martin (French), Martinique, Montserrat, Puerto Rico, St Maarten (Dutch), Trinidad & Tobago, St Vincent, Virgin Islands (UK), Virgin Islands (US)
Principal Cities: The largest city in the AST time zone is Santo Domingo in Dominican Republic, with about 2.202 million people. Other major cities in this time zone include Santiago de los Caballeros, Santo Domingo Oeste, San Juan, Halifax.
French: HNA - Heure Normale de l'Atlantique
Spanish: AST - Tiempo Estándar del Atlántico
Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Atlantic Daylight Time (ADT).
Start: Atlantic Standard Time (AST) started on Sunday, November 2, 2025 at 2:00 am local time and clocks were set one hour back to Sunday, November 2, 2025, 1:00 am. Standard time starts annually on the first Sunday of November.
End: Atlantic Standard Time (AST) ends on Sunday, March 8, 2026 at 2:00 am local time and clocks are set one hour forward to Sunday, March 8, 2026, 3:00 am local daylight time instead. Standard time ends annually on the second Sunday of March.
AST representations, usage and related time zones
- -04 - basic short
- -0400 - basic
- -04:00 - extended
- -0400 - sign character (-) followed by a four digit time providing hours (04) and minutes (00) of the offset. Indicates an offset of four hours to the west of the zero meridian.
- Quebec - Military abbreviation for AST
- Q - short form of 'Quebec'
- America/Anguilla
- America/Antigua
- America/Aruba
- America/Barbados
- America/Blanc-Sablon
- America/Curacao
- America/Dominica
- America/Glace_Bay
- America/Goose_Bay
- America/Grenada
- America/Guadeloupe
- America/Halifax
- America/Kralendijk
- America/Lower_Princes
- America/Marigot
- America/Martinique
- America/Moncton
- America/Montserrat
- America/Port_of_Spain
- America/Puerto_Rico
- America/Santo_Domingo
- America/St_Barthelemy
- America/St_Kitts
- America/St_Lucia
- America/St_Thomas
- America/St_Vincent
- America/Thule
- America/Tortola
- America/Virgin
- Atlantic/Bermuda
- Canada/Atlantic
- Atlantic Standard Time - UTC -4
- Arabia Standard Time - UTC +3
- AST - Atlantic Standard Time
- EDT - Eastern Daylight Time
- AMT - Amazon Time
- BOT - Bolivia Time
- CDT - Cuba Daylight Time
- CLT - Chile Standard Time
- FKT - Falkland Island Time
- GYT - Guyana Time
- HLV - Hora Legal de Venezuela
- PYT - Paraguay Time
- Q - Quebec Time Zone
- VET - Venezuelan Standard Time