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CT/CDT
12am
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AST
UTC−4
1h ahead
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Quick answers

Selected conversion

7:00 am07:00 CDT (UTC-5), Oct 19, 2026 = 8:00 am08:00 AST (UTC-4), Oct 19, 2026

CDT is 1 hour behind AST.

How the time difference changes

For most of the year, CT is 1 hour behind AST Caribbean. From Nov 1, 2026 to Mar 14, 2027, CT is 2 hours behind AST Caribbean.

For most of the year, working hours of 9:00 am to 6:00 pm in CT correspond to 10:00 am to 7:00 pm in AST Caribbean. At other times of the year, working hours of 9:00 am to 6:00 pm in CT correspond to 11:00 am to 8:00 pm in AST Caribbean.For most of the year, working hours of 09:00 to 18:00 in CT correspond to 10:00 to 19:00 in AST Caribbean. At other times of the year, working hours of 09:00 to 18:00 in CT correspond to 11:00 to 20:00 in AST Caribbean.

Compare CT time with AST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.

Time Difference

Central Daylight Time is 1 hour behind Atlantic Standard Time.
7:00 am07:00 in CDT is 8:00 am08:00 in AST

CDT to AST call time
Best time for a conference call or a meeting is between 9am-5pm09:00-17:00 in CDT which corresponds to 10am-6pm10:00-18:00 in AST

7:00 am07:00 Central Daylight Time (CDT). Offset UTC -5:00 hours
8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours

7:00 am07:00 CDT / 8:00 am08:00 AST

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Hourly time comparison
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Central Time

Central Time (CT) is a general term used to describe the areas that observe either the Central Standard Time (CST) or Central Daylight Time (CDT) in the United States and Canada. CT is not static but switches between CDT and CST.

Territories observing the time zone are primarily in North and Central America. It runs through several Mexican and U.S. states, as well as several Canadian provinces and Central American countries.

Countries using this time zone: Belize, Canada, Costa Rica, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, United States

Principal Cities: The largest city in the CT time zone is Mexico City in Mexico, with about 12.294 million people. Other major cities in this time zone include Chicago, Houston, Puebla, Santiago de Querétaro.

French: HNC - Heure Normale du Centre

Spanish: CT - Tiempo Central Estándar, CT - Zona Centro

Map of the areas on Central Time (CT)
CT all year CT part of the year

Today the lighter areas are on UTC−6 (Central Standard Time, MDT).

CT 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 CT
  • S - short form of 'Sierra'
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).

Countries using this time zone: Anguilla, Antigua and Barbuda, Aruba, Barbados, Bermuda, British Virgin Islands, Canada, Caribbean Netherlands, Curaçao, Dominica, Dominican Republic, Greenland, Grenada, Guadeloupe, Martinique, Montserrat, Puerto Rico, Saint Barthélemy, Saint Kitts and Nevis, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Maarten, Trinidad and Tobago, US Virgin Islands

Principal Cities: The largest city in the AST time zone is Santo Domingo in the Dominican Republic, with about 2.202 million people. Other major cities in this time zone include Santiago de los Caballeros, Halifax, San Juan, San Pedro de Macorís.

Daylight Saving: Some places on Atlantic Standard Time (AST) keep the same time all year, while others use AST for only part of the year and change their clocks for daylight saving time; see upcoming clock changes worldwide.

Map of the areas on Atlantic Standard Time (AST)
AST all year AST part of the year

Today the lighter areas are on UTC−3 (ADT).

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
  • GYT - Guyana Time
  • HLV - Hora Legal de Venezuela
  • Q - Quebec Time Zone
  • VET - Venezuelan Standard Time