BST to ADT Converter
Start by searching for a time zone, city, or town.
Add one or more places to compare local times, adjust the date, and share the result.
Quick answers
Selected conversion
12:00 pm12:00 GMT (UTC+0), Oct 31, 2026 = 9:00 am09:00 ADT (UTC-3), Oct 31, 2026
GMT is 3 hours ahead of ADT.
BST and ADT examples
These examples always use BST (UTC+1) and ADT (UTC-3). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
BST is 4 hours ahead of ADT.
How the time difference changes
For most of the year, BST is 4 hours ahead of ADT. From Oct 25 to Nov 1, 2026, from Mar 14 to Mar 28, 2027, and from Oct 31 to Nov 7, 2027, GMT is 3 hours ahead of ADT. From Nov 1, 2026 to Mar 14, 2027, GMT is 4 hours ahead of AST.
For most of the year, working hours of 9:00 am to 6:00 pm in BST correspond to 5:00 am to 2:00 pm in ADT. At other times of the year, working hours of 9:00 am to 6:00 pm in GMT correspond to 5:00 am to 2:00 pm in AST or working hours of 9:00 am to 6:00 pm in GMT correspond to 6:00 am to 3:00 pm in ADT.For most of the year, working hours of 09:00 to 18:00 in BST correspond to 05:00 to 14:00 in ADT. At other times of the year, working hours of 09:00 to 18:00 in GMT correspond to 05:00 to 14:00 in AST or working hours of 09:00 to 18:00 in GMT correspond to 06:00 to 15:00 in ADT.
Compare BST time with ADT time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Greenwich Mean Time is 3 hours ahead of Atlantic Daylight Time.
12:00 pm12:00 in GMT is 9:00 am09:00 in ADT
GMT to ADT call time
Best time for a conference call or a meeting is between 12pm-6pm12:00-18:00 in GMT which corresponds to 9am-3pm09:00-15:00 in ADT
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
12:00 pm12:00 GMT / 9:00 am09:00 ADT
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.
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British Summer Time
Offset: BST is 1 hour ahead of Greenwich Mean Time (GMT).
Countries using this time zone: Guernsey, Isle of Man, Jersey, United Kingdom
Principal Cities: The largest city in the BST time zone is London in the United Kingdom, with about 8.962 million people. Other major cities in this time zone include Birmingham, Glasgow, Manchester, Sheffield.
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 the two are the same. In the military, GMT is known as Zulu time. Greenwich Mean Time was the same as Universal Time (UT), a standard astronomical concept used in many technical fields, until the introduction of UTC in 1972.
Current time in the United Kingdom: UK time now
Today the shaded areas are on UTC+0 (GMT).
BST representations, usage and related time zones
- +01 - basic short
- +0100 - basic
- +01:00 - extended
- +0100 - sign character (+) followed by a four digit time providing hours (01) and minutes (00) of the offset. Indicates an offset of one hour to the east of the zero meridian.
- Alpha - Military abbreviation for BST
- A - short form of 'Alpha'
- Europe/Belfast
- Europe/Guernsey
- Europe/Isle_of_Man
- Europe/Jersey
- Europe/London
- GB
- GB-Eire
- British Summer Time - UTC +1
- Bangladesh Standard Time - UTC +6
- Bougainville Standard Time - UTC +11
- 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
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
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).
Start: 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.
End: 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
- -03 - basic short
- -0300 - basic
- -03:00 - extended
- -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.
- Papa - Military abbreviation for ADT
- P - short form of 'Papa'
- America/Glace_Bay
- America/Goose_Bay
- America/Halifax
- America/Moncton
- America/Thule
- Atlantic/Bermuda
- Canada/Atlantic
- 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