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ADT to GMT Converter

Updating current time…
ADT
Atlantic Daylight Time
GMT -3
12am
3am
6am
9am
12pm
3pm
6pm
9pm
GMT
Greenwich Mean Time
GMT +0
12am
3am
6am
9am
12pm
3pm
6pm
9pm
The United Kingdom is on summer time: BST (UTC+1) until Sun, Oct 25.

Iceland and Ghana stay on GMT (UTC+0).

Iceland, Ghana · GMT all year (UTC+0)United Kingdom · BST (UTC+1)

Quick answers

Selected conversion

9:00 am09:00 ADT (UTC-3), Oct 7, 2026 = 12:00 pm12:00 GMT (UTC+0), Oct 7, 2026

ADT is 3 hours behind GMT.

ADT and GMT examples

These examples always use ADT (UTC-3) and GMT (UTC+0). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.

ADT is 3 hours behind GMT.

How the time difference changes

For most of the year, ADT is 3 hours behind GMT. At other times of the year, AST is 4 hours behind GMT.

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 GMT. 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 GMT.For most of the year, working hours of 09:00 to 17:00 in ADT correspond to 12:00 to 20:00 in GMT. At other times of the year, working hours of 09:00 to 17:00 in AST correspond to 13:00 to 21:00 in GMT.

Compare ADT time with GMT 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 Greenwich Mean Time.
9:00 am09:00 in ADT is 12:00 pm12:00 in GMT

ADT to GMT 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 GMT

9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours

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

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

Atlantic Daylight Time

Offset: ADT is 3 hours behind Greenwich Mean Time (GMT) and is used in North America

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, Dartmouth, Moncton, Saint John.

French: HAA - Heure Avancée de l'Atlantique

ADT Time Zone Geo Map
ADT timezone map

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).

Daylight saving time clock moves forward for one hourStart: 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.

Daylight saving time clock moves back for one hourEnd: 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 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 - Brasília time
  • CLST - Chile Summer Time
  • FKST - Falkland Islands Summer Time
  • GFT - French Guiana Time
  • P - Papa Time Zone
  • PYST - Paraguay Summer Time
  • SRT - Suriname Time
  • UYT - Uruguay Time

Greenwich Mean Time

Offset: GMT is 0 hours ahead Greenwich Mean Time (GMT) and is used in Europe

Countries using this time zone: Burkina Faso, Côte d'Ivoire, Britain (UK), Guernsey, Ghana, Greenland, Gambia, Guinea, Guinea-Bissau, Ireland, Isle of Man, Iceland, Jersey, Liberia, Mali, Mauritania, St Helena, Sierra Leone, Senegal, Sao Tome & Principe, Togo

Principal Cities: The largest city in the GMT time zone is London in United Kingdom, with about 8.962 million people. Other major cities in this time zone include Abidjan, Bamako, Dakar, Kumasi.

Greenwich Mean Time (GMT) originally referred to the mean solar time at the Royal Observatory in Greenwich, London. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone, and in casual use for the most parts it is the same. In military GMT is known as Zulu time.Greenwich Mean Time was the same as Universal Time (UT), until the introduction of UTC in 1972 a standard astronomical concept used in many technical fields.

GMT Time Zone Geo Map
GMT timezone map

GMT 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 GMT
  • Z - short form of 'Zulu'
IANA/Olson: Reflects GMT time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Africa/Abidjan
  • Africa/Accra
  • Africa/Bamako
  • Africa/Banjul
  • Africa/Bissau
  • Africa/Conakry
  • Africa/Dakar
  • Africa/Freetown
  • Africa/Lome
  • Africa/Monrovia
  • Africa/Nouakchott
  • Africa/Ouagadougou
  • Africa/Sao_Tome
  • Africa/Timbuktu
  • America/Danmarkshavn
  • Atlantic/Reykjavik
  • Atlantic/St_Helena
  • Eire
  • Etc/GMT
  • Etc/GMT+0
  • Etc/GMT-0
  • Etc/GMT0
  • Etc/Greenwich
  • Europe/Belfast
  • Europe/Dublin
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire
  • GMT
  • GMT+0
  • GMT-0
  • GMT0
  • Greenwich
  • Iceland
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 - Universal Time Coordinated
  • WT - Western Sahara Standard Time
  • Z - Zulu Time Zone
EST to ISTGMT to ESTPST to ESTEST to GMTPST to GMT