AST to CDT Converter
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Add one or more places to compare local times, adjust the date, and share the result.
Quick answers
Selected conversion
9:00 am09:00 ADT (UTC-3), Oct 18, 2026 = 7:00 am07:00 CDT (UTC-5), Oct 18, 2026
ADT is 2 hours ahead of CDT.
AST and CDT examples
These examples always use AST (UTC-4) and CDT (UTC-5). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
AST is 1 hour ahead of CDT.
How the time difference changes
For most of the year, ADT is 2 hours ahead of CDT. From Nov 1, 2026 to Mar 14, 2027, AST is 2 hours ahead of CST. Briefly around clock changes, ADT is 3 hours ahead of CST or AST is 1 hour ahead of CDT.
For most of the year, working hours of 9:00 am to 6:00 pm in ADT correspond to 7:00 am to 4:00 pm in CDT. At other times of the year, working hours of 9:00 am to 6:00 pm in AST correspond to 7:00 am to 4:00 pm in CST.For most of the year, working hours of 09:00 to 18:00 in ADT correspond to 07:00 to 16:00 in CDT. At other times of the year, working hours of 09:00 to 18:00 in AST correspond to 07:00 to 16:00 in CST.
Compare AST time with CDT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Atlantic Daylight Time is 2 hours ahead of Central Daylight Time.
9:00 am09:00 in ADT is 7:00 am07:00 in CDT
ADT to CDT call time
Best time for a conference call or a meeting is between 11am-6pm11:00-18:00 in ADT which corresponds to 9am-4pm09:00-16:00 in CDT
9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
7:00 am07:00 Central Daylight Time (CDT). Offset UTC -5:00 hours
9:00 am09:00 ADT / 7:00 am07:00 CDT
Choose an hour to update the converter. Day labels such as “next day” or “+1” are relative to the selected date in the first column. Use Up and Down arrow keys, Home or End to move between hours, then Enter or Space to select.
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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.
French: HNA - Heure Normale de l'Atlantique
Spanish: AST - Tiempo Estándar del Atlántico
Today the lighter areas are on UTC−3 (ADT).
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).
End: 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.
Start: 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 Canada daylight saving time and upcoming clock changes worldwide.
AST representations, usage and related time zones
- -04 - basic short
- -0400 - basic
- -04:00 - extended
- -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.
- Quebec - Military abbreviation for AST
- Q - short form of 'Quebec'
- 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
- Atlantic Standard Time - UTC -4
- Arabia Standard Time - UTC +3
- 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
Central Daylight Time
Offset: CDT is 5 hours behind Greenwich Mean Time (GMT).
Countries using this time zone: Canada, Mexico, United States
Principal Cities: The largest city in the CDT time zone is Chicago in the United States, with about 2.664 million people. Other major cities in this time zone include Houston, San Antonio, Dallas, Fort Worth.
French: HAC - Heure Avancée du Centre
Spanish: CT - Zona Centro
Today all shaded areas are on CDT.
Daylight Saving: Central Daylight Time (CDT) is a daylight saving/summer time zone. During winter, some places set clocks back one hour and observe Central Standard Time (CST).
Start: Central Daylight Time (CDT) started 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. Daylight saving starts annually on the second Sunday of March.
End: Central Daylight Time (CDT) ends 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 local standard time instead. Daylight saving ends annually on the first Sunday of November.
See USA daylight saving time and upcoming clock changes worldwide.
CDT representations, usage and related time zones
- -05 - basic short
- -0500 - basic
- -05:00 - extended
- -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.
- Romeo - Military abbreviation for CDT
- R - short form of 'Romeo'
- America/Chicago
- America/Indiana/Knox
- America/Indiana/Tell_City
- America/Knox_IN
- America/Matamoros
- America/Menominee
- America/North_Dakota/Beulah
- America/North_Dakota/Center
- America/North_Dakota/New_Salem
- America/Ojinaga
- America/Rainy_River
- America/Rankin_Inlet
- America/Resolute
- America/Winnipeg
- CST6CDT
- Canada/Central
- US/Central
- US/Indiana-Starke
- Central Daylight Time - UTC -5
- Cuba Daylight Time - UTC -4
- 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