|
CDT
Central Daylight Time
GMT -5:00 h
AST
Atlantic Standard Time
GMT -4:00 h
AST is NOT in use by many locations
ADT (Atlantic Daylight Time) is used instead. Switch to ADT time zone or select one of the cities Santo Domingo, Santiago de los Caballeros, Santo Domingo Oeste for automatic timezone change.

Time Difference

Central Daylight Time is 1 hours behind of Atlantic Standard Time
So 5:21 AM05:21 in CDT is 6:21 AM06:21 in AST

5:21 AM05:21 Central Daylight Time (CDT). Offset UTC -5:00 hours
6:21 AM06:21 Atlantic Standard Time (AST). Offset UTC -4:00 hours

5:21 AM05:21 CDT / 6:21 AM06:21 AST

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

Central Daylight Time

Offset: CDT is 5 hours behind Greenwich Mean Time (GMT) and is used in North America

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

Principal Cities: The largest city in the CDT 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: Central Daylight Time (CDT) is a daylight saving/summer timezone, however during winter some places switch clocks for one hour back and observe Central Standard Time (CST).

Start: Central Daylight Time (CDT) starts annually on the same date and time. and clocks were set one hour forward on Sunday, March 10, 2019, at 2:00 (2:00 am) local time.

End: Central Daylight Time (CDT) ends annually on the same date and time. and clocks are set one hour back on Sunday, November 3, 2019, at 2:00 (2:00 am) local time.

French: HAC - Heure Avancée du Centre

Spanish: CT - Zona Centro

CDT Time Zone Geo Map
CDT timezone map
CDT 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 CDT
  • R - short form of 'Romeo'

IANA/Olson: Reflects CDT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Bahia_Banderas
  • America/Chicago
  • America/Indiana/Knox
  • America/Indiana/Tell_City
  • America/Knox_IN
  • America/Matamoros
  • America/Menominee
  • America/Merida
  • America/Mexico_City
  • America/Monterrey
  • America/North_Dakota/Beulah
  • America/North_Dakota/Center
  • America/North_Dakota/New_Salem
  • America/Rainy_River
  • America/Rankin_Inlet
  • America/Resolute
  • America/Winnipeg
  • CST6CDT
  • Canada/Central
  • Mexico/General
  • US/Central
  • US/Indiana-Starke

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

  • Central Daylight Time - UTC -5:00 h
  • Cuba Daylight Time - UTC -4:00 h

Time zones with the GMT -5:00 h 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 ends annually on the same date and time. and clocks were set one hour forward on Sunday, March 10, 2019, at 2:00 (2:00 am) local time.

Start: AST starts annually on the same date and time. and clocks are set one hour back on Sunday, November 3, 2019, 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 -4:00 h
  • Arabia Standard Time - UTC +3:00 h

Time zones with the GMT -4:00 h 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
  • -04 -