MDT to ADT Converter
MDT is not used on this date
This converter uses MST (GMT -7), the offset Denver uses on this date. Open the MST converter.ADT is not used on this date
This converter uses AST (GMT -4), the offset Moncton uses on this date. Open the AST converter.Quick answers
For most of the year, MDT is 3 hours behind ADT. During seasonal clock changes, MST is 3 hours behind AST. Briefly around those 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. During seasonal clock changes, working hours of 9:00 am to 5:00 pm in MST correspond to 12:00 pm to 8:00 pm in AST.
Compare MDT time with ADT 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 Daylight Time
Offset: MDT is 6 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 MDT time zone is Calgary in Canada, with about 1.02 million people. Other major cities in this time zone include Edmonton, El Paso, Denver, Albuquerque.
French: HAR - Heure Avancée des Rocheuses
Spanish: MT - Zona Pacífico
Daylight Saving: Mountain Daylight Time (MDT) is a daylight saving/summer time zone, but some places set clocks back one hour during winter and observe Mountain Standard Time (MST).
End: Mountain Daylight Time (MDT) ended 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 local standard time instead. Daylight saving ends annually on the first Sunday of November
Start: Mountain Daylight Time (MDT) starts 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. Daylight saving starts annually on the second Sunday of March
MDT representations, usage and related time zones
- -06 - basic short
- -0600 - basic
- -06:00 - extended
- -0600 - sign character (-) followed by a four digit time providing hours (06) and minutes (00) of the offset. Indicates an offset of six hours to the west of the zero meridian.
- Sierra - Military abbreviation for MDT
- S - short form of 'Sierra'
- America/Boise
- America/Cambridge_Bay
- America/Ciudad_Juarez
- America/Denver
- America/Edmonton
- America/Inuvik
- America/Shiprock
- America/Yellowknife
- Canada/Mountain
- MST7MDT
- Navajo
- US/Mountain
- CST - Central Standard Time
- CT - Central Time
- MDT - Mountain Daylight Time
- EAST - Easter Island Standard Time
- GALT - Galapagos Time
- S - Sierra Time Zone
Atlantic Daylight Time
Offset: ADT is 3 hours behind Greenwich Mean Time (GMT) and is used in North America
Countries using this time zone: Bermuda, Canada, Greenland
Principal Cities: The largest city in the ADT time zone is Halifax in Canada, with about 359,111 people. Other major cities in this time zone include Sydney, Dartmouth, Saint John, Moncton.
French: HAA - Heure Avancée de l'Atlantique
Daylight Saving: Atlantic Daylight Time (ADT) is a daylight saving/summer time zone, but some places set clocks back one hour during winter and observe Atlantic Standard Time (AST).
End: Atlantic Daylight Time (ADT) ended 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 local standard time instead. Daylight saving ends annually on the first Sunday of November
Start: Atlantic Daylight Time (ADT) starts 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. Daylight saving starts annually on the second Sunday of March
ADT representations, usage and related time zones
- -03 - basic short
- -0300 - basic
- -03:00 - extended
- -0300 - sign character (-) followed by a four digit time providing hours (03) and minutes (00) of the offset. Indicates an offset of three hours to the west of the zero meridian.
- Papa - Military abbreviation for ADT
- P - short form of 'Papa'
- America/Glace_Bay
- America/Goose_Bay
- America/Halifax
- America/Moncton
- America/Thule
- Atlantic/Bermuda
- Canada/Atlantic
- ADT - Atlantic Daylight Time
- PMT - Pierre & Miquelon Standard Time
- PMST - Pierre & Miquelon Standard Time
- AMST - Amazon Summer Time
- ART - Argentina Time
- BRT - Brasília time
- CLST - Chile Summer Time
- FKST - Falkland Islands Summer Time
- GFT - French Guiana Time
- P - Papa Time Zone
- PYST - Paraguay Summer Time
- SRT - Suriname Time
- UYT - Uruguay Time