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CST Caribbean to AST Converter

Updating current time…
CDT/CST
Cuba Daylight Time
GMT -4
12am
3am
6am
9am
12pm
3pm
6pm
9pm
CST is not used on this date.

This converter uses CDT (UTC−4), as in Havana.

Keep CST (UTC−5)
ADT/AST
Atlantic Daylight Time
GMT -3
12am
3am
6am
9am
12pm
3pm
6pm
9pm
Atlantic Time is on daylight saving time: ADT (UTC−3) until Sun, Nov 1.
Use AST all year (UTC−4)

Quick answers

Selected conversion

8:00 am08:00 CDT (UTC-4), Oct 12, 2026 = 9:00 am09:00 ADT (UTC-3), Oct 12, 2026

CDT is 1 hour behind ADT.

CST and AST examples

These examples always use CST (UTC-5) and AST (UTC-4). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

CST is 1 hour behind AST.

How the time difference changes

For most of the year, CDT Caribbean is 1 hour behind ADT. At other times of the year, CST Caribbean is 1 hour behind AST. Briefly around clock changes, CDT Caribbean and AST have the same time.

For most of the year, working hours of 9:00 am to 5:00 pm in CDT Caribbean correspond to 10:00 am to 6:00 pm in ADT. At other times of the year, working hours of 9:00 am to 5:00 pm in CST Caribbean correspond to 10:00 am to 6:00 pm in AST.For most of the year, working hours of 09:00 to 17:00 in CDT Caribbean correspond to 10:00 to 18:00 in ADT. At other times of the year, working hours of 09:00 to 17:00 in CST Caribbean correspond to 10:00 to 18:00 in AST.

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

Time Difference

Cuba Daylight Time is 1 hour behind Atlantic Daylight Time.
8:00 am08:00 in CDT is 9:00 am09:00 in ADT

CDT to ADT call time
Best time for a conference call or a meeting is between 9am-4pm09:00-16:00 in CDT which corresponds to 10am-5pm10:00-17:00 in ADT

8:00 am08:00 Cuba Daylight Time (CDT). Offset UTC -4:00 hours
9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours

8:00 am08:00 CDT / 9:00 am09:00 ADT

CDTADT
12:00am1:00am
1:00am2:00am
2:00am3:00am
3:00am4:00am
4:00am5:00am
5:00am6:00am
6:00am7:00am
7:00am8:00am
8:00am9:00am
9:00am10:00am
10:00am11:00am
11:00am12:00pm
12:00pm1:00pm
1:00pm2:00pm
2:00pm3:00pm
3:00pm4:00pm
4:00pm5:00pm
5:00pm6:00pm
6:00pm7:00pm
7:00pm8:00pm
8:00pm9:00pm
9:00pm10:00pm
10:00pm11:00pm
11:00pm12:00am
00:0001:00
01:0002:00
02:0003:00
03:0004:00
04:0005:00
05:0006:00
06:0007:00
07:0008:00
08:0009:00
09:0010:00
10:0011:00
11:0012:00
12:0013:00
13:0014:00
14:0015:00
15:0016:00
16:0017:00
17:0018:00
18:0019:00
19:0020:00
20:0021:00
21:0022:00
22:0023:00
23:0000:00

Cuba Standard Time

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

Countries using this time zone: Canada, Cuba, Mexico, United States

Principal Cities: The largest city in the CST time zone is Chicago in the United States, with about 2.664 million people. Other major cities in this time zone include Havana, Houston, San Antonio, Ciudad Juarez.

CST Time Zone Geo Map
CST 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 Cuba Daylight Time (CDT).

Daylight saving time clock moves forward for one hourEnd: Cuba Standard Time (CST) ended on Sunday, March 8, 2026 at 12:00 am00:00 local time and clocks were set one hour forward to Sunday, March 8, 2026, 1:00 am01:00 local daylight time instead. Standard time ends annually on the second Sunday of March.

Daylight saving time clock moves back for one hourStart: Cuba Standard Time (CST) starts on Sunday, November 1, 2026 at 1:00 am01:00 local time and clocks are set one hour back to Sunday, November 1, 2026, 12:00 am00:00. Standard time starts annually on the first Sunday of November.

See upcoming clock changes worldwide.

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 an offset of five hours 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

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, Halifax, San Juan.

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 forward for one hourEnd: Atlantic Standard Time (AST) ended on Sunday, March 8, 2026 at 2:00 am02:00 local time and clocks were set one hour forward to Sunday, March 8, 2026, 3:00 am03:00 local daylight time instead. Standard time ends annually on the second Sunday of March.

Daylight saving time clock moves back for one hourStart: Atlantic Standard Time (AST) starts on Sunday, November 1, 2026 at 2:00 am02:00 local time and clocks are set one hour back to Sunday, November 1, 2026, 1:00 am01:00. Standard time starts annually on the first Sunday of November.

See upcoming clock changes worldwide.

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