AST to UTC Converter

Updating current time…
ADT/AST
Atlantic Daylight Time
UTC−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)
UTC
Coordinated Universal Time
UTC+0
12am
3am
6am
9am
12pm
3pm
6pm
9pm

Quick answers

Selected conversion

9:00 am09:00 ADT (UTC-3), Oct 12, 2026 = 12:00 pm12:00 UTC (UTC+0), Oct 12, 2026

ADT is 3 hours behind UTC.

AST and UTC examples

These examples always use AST (UTC-4) and UTC (UTC+0). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

AST is 4 hours behind UTC.

How the time difference changes

For most of the year, ADT is 3 hours behind UTC. From Nov 1, 2026 to Mar 14, 2027, AST is 4 hours behind UTC.

For most of the year, working hours of 9:00 am to 5:00 pm in ADT correspond to 12:00 pm to 8:00 pm in UTC. At other times of the year, working hours of 9:00 am to 5:00 pm in AST correspond to 1:00 pm to 9:00 pm in UTC.For most of the year, working hours of 09:00 to 17:00 in ADT correspond to 12:00 to 20:00 in UTC. At other times of the year, working hours of 09:00 to 17:00 in AST correspond to 13:00 to 21:00 in UTC.

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

Time Difference

Atlantic Daylight Time is 3 hours behind Coordinated Universal Time.
9:00 am09:00 in ADT is 12:00 pm12:00 in UTC

ADT to UTC call time
Best time for a conference call or a meeting is between 9am-2pm09:00-14:00 in ADT which corresponds to 12pm-5pm12:00-17:00 in UTC

9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
12:00 pm12:00 Coordinated Universal Time (UTC). Offset UTC 0:00 hours

9:00 am09:00 ADT / 12:00 pm12:00 UTC

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
ADTUTC
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Atlantic Standard Time

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

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 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).

Open the world time zone map© OpenStreetMap

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 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

Coordinated Universal Time

Offset: UTC is the same as Greenwich Mean Time (GMT).

Coordinated Universal Time (UTC) is the world time standard that regulates clocks and time. It is the successor to Greenwich Mean Time (GMT). For casual use, UTC is the same as GMT, but UTC is the standard the scientific community uses.
UTC has been the time standard commonly used across the world since 1972. It is used in many technical fields, such as aviation and meteorology, and to synchronize time across internet networks.

Map of the areas on Coordinated Universal Time (UTC)
UTC all year UTC part of the year

Today some of the lighter areas are on UTC+1 (British Summer Time, Irish Standard Time, WEST).

Open the world time zone map© OpenStreetMap

UTC representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • Z - is the zone designator for the zero UTC/GMT offset, also known as 'Zulu' time
  • +00 - basic short
  • +0000 - basic
  • +00:00 - extended
Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0000 - sign character (+) followed by a four digit time providing hours (00) and minutes (00) of the offset. Indicates the zero UTC/GMT offset.
Military/NATO: Used by the U.S. military, Chinese military and others
  • Zulu - Military abbreviation for UTC
  • Z - short form of 'Zulu'
IANA/Olson: Reflects UTC time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Etc/UCT
  • Etc/UTC
  • Etc/Universal
  • Etc/Zulu
  • UCT
  • UTC
  • Universal
  • Zulu
Time zones with the GMT +0 offset:
  • EGST - Eastern Greenland Summer Time
  • GMT - Greenwich Mean Time
  • WET - Western European Time
  • AZOST - Azores Summer Time
  • UTC - Coordinated Universal Time
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone
EST to ISTGMT to ESTPST to ESTEST to GMTPST to GMT