AST
Amazon Standard Time
GMT -4
MST/MDT
Mountain Standard Time
GMT -7
MDT automatically adjusted to MST time zone, that is in use

Time Difference

Amazon Standard Time is 3 hours ahead of Mountain Standard Time
4:00 am04:00 in AST is 1:00 am01:00 in MST

AST to MDT call time
Best time for a conference call or a meeting is between 10am-6pm in AST which corresponds to 8am-4pm in MDT

4:00 am04:00 Amazon Standard Time (AST). Offset UTC -4:00 hours
1:00 am01:00 Mountain Standard Time (MST). Offset UTC -7:00 hours

4:00 am04:00 AST / 1:00 am01:00 MST

AST MST
12am (midnight) 9pm
1am 10pm
2am 11pm
3am 12am (midnight)
4am 1am
5am 2am
6am 3am
7am 4am
8am 5am
9am 6am
10am 7am
11am 8am
12pm (noon) 9am
1pm 10am
2pm 11am
3pm 12pm (noon)
4pm 1pm
5pm 2pm
6pm 3pm
7pm 4pm
8pm 5pm
9pm 6pm
10pm 7pm
11pm 8pm
0:00 21:00
1:00 22:00
2:00 23:00
3:00 0:00
4:00 1:00
5:00 2:00
6:00 3:00
7:00 4:00
8:00 5:00
9:00 6:00
10:00 7:00
11:00 8:00
12:00 9:00
13:00 10:00
14:00 11:00
15:00 12:00
16:00 13:00
17:00 14:00
18:00 15:00
19:00 16:00
20:00 17:00
21:00 18:00
22:00 19:00
23:00 20:00

Amazon Standard Time

Offset: AST is 4 hours behind Greenwich Mean Time (GMT) and is used in America

Countries: It is used in following countries: 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 timezone is Santo Domingo from Dominican Republic with population about 2.202 million people. Other major cities in the area are Santiago de los Caballeros, Santo Domingo Oeste, San Juan, Halifax

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 four hour and zero minutes time differences 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
  • Arabian Standard Time - UTC +3
  • Amazon Standard Time - UTC -4
  • Apia Standard Time - UTC +13
  • Azores Standard Time - UTC -1
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

Mountain Daylight Time

Offset: MDT is 6 hours behind Greenwich Mean Time (GMT) and is used in North America

Countries: It is used in following countries: Canada, Mexico, United States

Principal Cities: The largest city in the MDT timezone is Ciudad Juarez from Mexico with population about 1.512 million people. Other major cities in the area are Calgary, Chihuahua, Edmonton, El Paso

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, however during winter some places adjust time for one hour back and observe Mountain Standard Time (MST).

Daylight saving time clock moves back for one hour from 2am to 1amEnd: Mountain Daylight Time (MDT) has ended on Sunday, November 7, 2021 at 2:00 am local time and clocks were set one hour back to Sunday, November 7, 2021, 1:00 am local standard time instead. Daylight saving ends annually the on first Sunday of November

Daylight saving time clock moves forward for one hour from 2am to 3amStart: Mountain Daylight Time (MDT) starts on Sunday, March 13, 2022 at 2:00 am local time and clocks are set one hour forward to Sunday, March 13, 2022, 3:00 am. Daylight saving starts annually the on 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 six hour and zero minutes time differences 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/Chihuahua
  • America/Denver
  • America/Edmonton
  • America/Inuvik
  • America/Mazatlan
  • America/Ojinaga
  • America/Shiprock
  • America/Yellowknife
  • Canada/Mountain
  • MST7MDT
  • Mexico/BajaSur
  • 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