|

MDT to AST Converter

MST/MDT
Mountain Standard Time
GMT -7
12am
3am
6am
9am
12pm
3pm
6pm
9pm
MDT is not used on this date
This converter uses MST (GMT -7), the offset Denver uses on this date. Open the MST converter.
AST
Atlantic Standard Time
GMT -4
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Compare MDT 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

MSTAST
12am (midnight)3am
1am4am
2am5am
3am6am
4am7am
5am8am
6am9am
7am10am
8am11am
9am12pm (noon)
10am1pm
11am2pm
12pm (noon)3pm
1pm4pm
2pm5pm
3pm6pm
4pm7pm
5pm8pm
6pm9pm
7pm10pm
8pm11pm
9pm12am (midnight)
10pm1am
11pm2am
00:0003:00
01:0004:00
02:0005:00
03:0006:00
04:0007:00
05:0008:00
06:0009:00
07:0010:00
08:0011:00
09:0012:00
10:0013:00
11:0014:00
12:0015:00
13:0016:00
14:0017:00
15:0018:00
16:0019:00
17:0020:00
18:0021:00
19:0022:00
20:0023:00
21:0000:00
22:0001:00
23:0002:00

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

MDT Time Zone Geo Map
MDT timezone map

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).

Daylight saving time clock moves forward for one hour from 2am to 3amEnd: 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

Daylight saving time clock moves back for one hour from 2am to 1amStart: 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

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -06 - basic short
  • -0600 - basic
  • -06:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -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.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Sierra - Military abbreviation for MDT
  • S - short form of 'Sierra'
IANA/Olson: Reflects MDT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Boise
  • America/Cambridge_Bay
  • America/Ciudad_Juarez
  • America/Denver
  • America/Edmonton
  • America/Inuvik
  • America/Shiprock
  • America/Yellowknife
  • Canada/Mountain
  • MST7MDT
  • Navajo
  • US/Mountain
Time zones with the GMT -6 offset:
  • CST - Central Standard Time
  • CT - Central Time
  • MDT - Mountain Daylight Time
  • EAST - Easter Island Standard Time
  • GALT - Galapagos Time
  • S - Sierra 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

AST Time Zone Geo Map
AST timezone map

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).

Daylight saving time clock moves back for one hour from 2am to 1amStart: 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.

Daylight saving time clock moves forward for one hour from 2am to 3amEnd: 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

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -04 - basic short
  • -0400 - basic
  • -04:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -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.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Quebec - Military abbreviation for AST
  • Q - short form of 'Quebec'
IANA/Olson: Reflects AST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • 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
AST Abbreviation: Several time zones share AST abbreviation and it could refer to these time zones
  • Atlantic Standard Time - UTC -4
  • Arabia Standard Time - UTC +3
Time zones with the GMT -4 offset:
  • 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
EST to ISTGMT to ESTPST to ESTEST to GMTPST to GMT