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ADT
12am
3am
6am
9am
12pm
3pm
6pm
9pm
EDT/EST
UTC−4
1h behind
12am
3am
6am
9am
12pm
3pm
6pm
9pm
Eastern Time is on daylight saving time: EDT (UTC−4) until Sun, Nov 1.

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.

ADT and EST (US winter time, UTC-5) examples

These examples always use ADT (UTC-3) and EST (UTC-5). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

ADT is 2 hours ahead of EST.

EST is US Eastern winter time (early November to mid-March). The rest of the year New York uses EDT (UTC-4), one hour later. For Eastern Time that follows daylight saving time, use ADT to ET. For daylight-time examples, use ADT to EDT.

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 ADT time with EST 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
ADTEDT
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23:00 previous day
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Atlantic Daylight Time

Offset: ADT is 3 hours behind Greenwich Mean Time (GMT).

Countries using this time zone: Bermuda, Canada, Greenland

Principal Cities: The largest city in the ADT time zone is Halifax in Canada, with about 471,559 people. Other major cities in this time zone include Sydney, Moncton, Saint John, Fredericton.

French: HAA - Heure Avancée de l'Atlantique

Map of the areas on Atlantic Daylight Time (ADT)
ADT part of the year

Today all shaded areas are on ADT.

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

123456789101112Start: Atlantic Daylight Time (ADT) 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: Atlantic Daylight Time (ADT) 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 Canada daylight saving time and upcoming clock changes worldwide.

ADT representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • -03 - basic short
  • -0300 - basic
  • -03:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • -0300 - sign character (-) followed by a four digit time providing hours (03) and minutes (00) of the offset. Indicates an offset of three hours to the west of the zero meridian.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Papa - Military abbreviation for ADT
  • P - short form of 'Papa'
IANA/Olson: Reflects ADT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Glace_Bay
  • America/Goose_Bay
  • America/Halifax
  • America/Moncton
  • America/Thule
  • Atlantic/Bermuda
  • Canada/Atlantic
Time zones with the GMT -3 offset:
  • ADT - Atlantic Daylight Time
  • PMT - Pierre & Miquelon Standard Time
  • PMST - Pierre & Miquelon Standard Time
  • AMST - Amazon Summer Time
  • ART - Argentina Time
  • BRT - Brasilia Time
  • CLST - Chile Summer Time
  • FKST - Falkland Islands Summer Time
  • FKT - Falkland Islands Time
  • GFT - French Guiana Time
  • P - Papa Time Zone
  • PYST - Paraguay Summer Time
  • PYT - Paraguay Time
  • SRT - Suriname Time
  • UYT - Uruguay Time

Eastern Standard Time

Offset: EST is 5 hours behind Greenwich Mean Time (GMT).

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

Principal Cities: The largest city in the EST 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: HNE - Heure Normale de l'Est

Spanish: ET - Tiempo del Este, ET - Zona Sureste

Map of the areas on Eastern Standard Time (EST)
EST all year EST part of the year

Today the lighter areas are on UTC−4 (EDT).

Daylight Saving: This is a standard time zone. During summer, some places set clocks forward one hour for daylight saving time and observe Eastern Daylight Time (EDT).

123456789101112End: Eastern Standard Time (EST) 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: Eastern Standard Time (EST) 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 USA daylight saving time and upcoming clock changes worldwide.

EST 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 EST
  • R - short form of 'Romeo'
IANA/Olson: Reflects EST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • America/Atikokan
  • America/Cancun
  • America/Cayman
  • America/Coral_Harbour
  • 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/Jamaica
  • America/Kentucky/Louisville
  • America/Kentucky/Monticello
  • America/Louisville
  • America/Montreal
  • America/Nassau
  • America/New_York
  • America/Nipigon
  • America/Panama
  • America/Pangnirtung
  • America/Port-au-Prince
  • America/Thunder_Bay
  • America/Toronto
  • Canada/Eastern
  • EST
  • EST5EDT
  • Jamaica
  • US/East-Indiana
  • US/Eastern
  • US/Michigan
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