ADT
Atlantic Daylight Time
GMT -3
ADT is NOT in use by many locations
AST (Atlantic Standard Time) is used instead. Switch to AST time zone or select one of the cities Halifax, Sydney, Dartmouth for automatic timezone change.
GMT/BST
Greenwich Mean Time
GMT +0
BST automatically adjusted to GMT time zone, that is in use

Time Difference

Atlantic Daylight Time is 3 hours behind of Greenwich Mean Time
So 1:00 am01:00 in ADT is 4:00 am04:00 in GMT

1:00 am01:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
4:00 am04:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours

1:00 am01:00 ADT / 4:00 am04:00 GMT

ADT GMT
12am (midnight) 3am
1am 4am
2am 5am
3am 6am
4am 7am
5am 8am
6am 9am
7am 10am
8am 11am
9am 12pm (noon)
10am 1pm
11am 2pm
12pm (noon) 3pm
1pm 4pm
2pm 5pm
3pm 6pm
4pm 7pm
5pm 8pm
6pm 9pm
7pm 10pm
8pm 11pm
9pm 12am (midnight)
10pm 1am
11pm 2am
0:00 3:00
1:00 4:00
2:00 5:00
3:00 6:00
4:00 7:00
5:00 8:00
6:00 9:00
7:00 10:00
8:00 11:00
9:00 12:00
10:00 13:00
11:00 14:00
12:00 15:00
13:00 16:00
14:00 17:00
15:00 18:00
16:00 19:00
17:00 20:00
18:00 21:00
19:00 22:00
20:00 23:00
21:00 0:00
22:00 1:00
23:00 2:00

Atlantic Daylight Time

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

Countries: It is used in following countries: Bermuda, Canada, Greenland

Principal Cities: The largest city in the ADT timezone is Halifax from Canada with population about 359111 people. Other major cities in the area are Sydney, Dartmouth, Saint John, Moncton

Daylight Saving: Atlantic Daylight Time (ADT) is a daylight saving/summer timezone, however during winter some places adjust time for one hour back and observe Atlantic Standard Time (AST).

End: ADT ends annually on the same date and time. and clocks were set one hour back on Sunday, November 3, 2019, at 2:00 (2:00 am) local time.

Start: ADT starts annually on the same date and time. and clocks are set one hour forward on Sunday, March 8, 2020, at 2:00 (2:00 am) local time.

French: HAA - Heure Avancée de l'Atlantique

ADT Time Zone Geo Map
ADT timezone map
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 three hour and zero minutes time differences 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
  • WGT - West Greenland 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
  • -03 -
  • -02 -


British Summer Time

Offset: BST is 1 hour ahead Greenwich Mean Time (GMT) and is used in Europe

Countries: It is used in following countries: Britain (UK), Guernsey, Isle of Man, Jersey

Principal Cities: The largest city in the BST timezone is London from United Kingdom with population about 7.557 million people. Other major cities in the area are Birmingham, Glasgow, Liverpool, Saint Helier

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.

BST Time Zone Geo Map
BST timezone map
BST representations, usage and related time zones

W3C/ISO-8601: International standard covering representation and exchange of dates and time-related data
  • +01 - basic short
  • +0100 - basic
  • +01:00 - extended

Email/RFC-2822: Internet Message Format Date Standard, typically used for timestamps in email headers
  • +0100 - sign character (+) followed by a four digit time providing hours (01) and minutes (00) of the offset. Indicates one hour and zero minutes time differences to the east of the zero meridian.

Military/NATO: Used by the U.S. military, Chinese military and others
  • Alpha - Military abbreviation for BST
  • A - short form of 'Alpha'

IANA/Olson: Reflects BST time zone boundaries defined by political bodies, primarily intended for use with computer programs and operating systems
  • Europe/Belfast
  • Europe/Guernsey
  • Europe/Isle_of_Man
  • Europe/Jersey
  • Europe/London
  • GB
  • GB-Eire

BST Abbreviation: Several time zones share BST abbreviation and it could refer to these time zones

  • British Summer Time - UTC +1
  • Bangladesh Standard Time - UTC +6
  • Bougainville Standard Time - UTC +11

Time zones with the GMT +1 offset:

  • BST - British Summer Time
  • CET - Central European Time
  • IST - Irish Standard Time
  • WEST - Western European Summer Time
  • A - Alpha Time Zone
  • CET - Central European Time
  • MEZ - Mitteleuropäische Zeit
  • WAT - West Africa Time
  • WST - Western Sahara Summer Time
  • BMT - Biel Mean Time
  • +01 -