CDT/CST
Central Daylight Time
GMT -5
CST automatically adjusted to CDT time zone, that is in use
ADT/AST
Atlantic Daylight Time
GMT -3
AST automatically adjusted to ADT time zone, that is in use

Time Difference

Central Daylight Time is 2 hours behind of Atlantic Daylight Time
So 2:00 am02:00 in CDT is 4:00 am04:00 in ADT

2:00 am02:00 Central Daylight Time (CDT). Offset UTC -5:00 hours
4:00 am04:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours

2:00 am02:00 CDT / 4:00 am04:00 ADT

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

Cuba Standard Time

Offset: CST is 5 hours behind Greenwich Mean Time (GMT) and is used in Caribbean

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

Principal Cities: The largest city in the CST timezone is Mexico City from Mexico with population about 12.294 million people. Other major cities in the area are Chicago, Havana, Houston, Iztapalapa

Daylight Saving: This is a standard timezone, however during summer some places adjust time for one hour forward for daylight saving and observe Central Daylight Time (CDT).

End: CST ended and clocks were set one hour forward on Sunday, 08 March 2020, at 2:00 (2:00 am) local time.

Start: CST starts and clocks are set one hour back on Sunday, 01 November 2020, at 2:00 (2:00 am) local time.

CST Time Zone Geo Map
CST timezone map
CST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -05 - basic short
  • -0500 - basic
  • -05:00 - extended

Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0500 - sign character (-) followed by a four digit time providing hours (05) and minutes (00) of the offset. Indicates five 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
  • Romeo - Military abbreviation for CST
  • R - short form of 'Romeo'

IANA/Olson: Reflects CST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Havana
  • Cuba

CST Abbreviation: Several time zones share CST abbreviation and it could refer to these time zones

  • Central Standard Time - UTC -6
  • China Standard Time - UTC +8
  • Cuba Standard Time - UTC -5

Time zones with the GMT -5 offset:

  • CDT - Central Daylight Time
  • EST - Eastern Standard Time
  • ET - Eastern Time
  • COT - Colombia Time
  • CST - Cuba Standard Time
  • EASST - Easter Island Summer Time
  • ECT - Ecuador Time
  • PET - Peru Time
  • R - Romeo Time Zone
  • -05 -


Atlantic Standard Time

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

Daylight Saving: This is a standard timezone, however during summer some places adjust time for one hour forward for daylight saving and observe Atlantic Daylight Time (ADT).

End: AST ended and clocks were set one hour forward on Sunday, 08 March 2020, at 2:00 (2:00 am) local time.

Start: AST starts and clocks are set one hour back on Sunday, 01 November 2020, at 2:00 (2:00 am) local time.

French: HNA - Heure Normale de l'Atlantique

Spanish: AST - Tiempo Estándar del Atlántico

AST Time Zone Geo Map
AST timezone map
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

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
  • PYT - Paraguay Time
  • Q - Quebec Time Zone
  • VET - Venezuelan Standard Time
  • GMT - GMT-04:00
  • -04 -