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ADT/AST
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Atlantic Time is on daylight saving time: ADT (UTC−3) until Sun, Nov 1.
EDT
UTC−4
1h behind
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Quick answers

Selected conversion

9:00 am09:00 ADT (UTC-3), Oct 17, 2026 = 8:00 am08:00 EDT (UTC-4), Oct 17, 2026

ADT is 1 hour ahead of EDT.

AST and EDT examples

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

AST and EDT have the same local time.

How the time difference changes

For most of the year, ADT is 1 hour ahead of EDT. From Nov 1, 2026 to Mar 14, 2027, AST is 1 hour ahead of EST. Briefly around clock changes, ADT is 2 hours ahead of EST or AST and EDT have the same time.

For most of the year, working hours of 9:00 am to 6:00 pm in ADT correspond to 8:00 am to 5:00 pm in EDT. At other times of the year, working hours of 9:00 am to 6:00 pm in AST correspond to 8:00 am to 5:00 pm in EST.For most of the year, working hours of 09:00 to 18:00 in ADT correspond to 08:00 to 17:00 in EDT. At other times of the year, working hours of 09:00 to 18:00 in AST correspond to 08:00 to 17:00 in EST.

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

Time Difference

Atlantic Daylight Time is 1 hour ahead of Eastern Daylight Time.
9:00 am09:00 in ADT is 8:00 am08:00 in EDT

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

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

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

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.

Hourly time comparison
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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

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).

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).

123456789101112End: 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.

123456789101112Start: 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

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

Eastern Daylight Time

Offset: EDT is 4 hours behind Greenwich Mean Time (GMT).

Countries using this time zone: Bahamas, Canada, Haiti, Turks and Caicos Islands, United States

Principal Cities: The largest city in the EDT time zone is New York City in the United States, with about 8.804 million people. Other major cities in this time zone include Toronto, Montréal, Philadelphia, Port-au-Prince.

French: HAE - Heure Avancée de l'Est

Spanish: EDT - Tiempo de verano del Este, ET - Zona Sureste

Map of the areas on Eastern Daylight Time (EDT)
EDT part of the year

Today all shaded areas are on EDT.

Daylight Saving: Eastern Daylight Time (EDT) is a daylight saving/summer time zone. During winter, some places set clocks back one hour and observe Eastern Standard Time (EST).

123456789101112Start: Eastern Daylight Time (EDT) 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.

123456789101112End: Eastern Daylight Time (EDT) 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.

EDT 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 EDT
  • Q - short form of 'Quebec'
IANA/Olson: Reflects EDT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Detroit
  • America/Fort_Wayne
  • America/Grand_Turk
  • America/Indiana/Indianapolis
  • America/Indiana/Marengo
  • America/Indiana/Petersburg
  • America/Indiana/Vevay
  • America/Indiana/Vincennes
  • America/Indiana/Winamac
  • America/Indianapolis
  • America/Iqaluit
  • America/Kentucky/Louisville
  • America/Kentucky/Monticello
  • America/Louisville
  • America/Montreal
  • America/Nassau
  • America/New_York
  • America/Nipigon
  • America/Pangnirtung
  • America/Port-au-Prince
  • America/Thunder_Bay
  • America/Toronto
  • Canada/Eastern
  • EST5EDT
  • US/East-Indiana
  • US/Eastern
  • US/Michigan
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