AST to BST 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
9:00 am09:00 ADT (UTC-3), Oct 14, 2026 = 1:00 pm13:00 BST (UTC+1), Oct 14, 2026
ADT is 4 hours behind BST.
AST and BST examples
These examples always use AST (UTC-4) and BST (UTC+1). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
AST is 5 hours behind BST.
How the time difference changes
For most of the year, ADT is 4 hours behind BST. From Oct 25 to Nov 1, 2026, and from Mar 14 to Mar 28, 2027, ADT is 3 hours behind GMT. From Nov 1, 2026 to Mar 14, 2027, 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 1:00 pm to 9:00 pm in BST. 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 or working hours of 9:00 am to 5:00 pm in ADT correspond to 12:00 pm to 8:00 pm in GMT.For most of the year, working hours of 09:00 to 17:00 in ADT correspond to 13:00 to 21:00 in BST. 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 or working hours of 09:00 to 17:00 in ADT correspond to 12:00 to 20:00 in GMT.
Compare AST time with BST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Atlantic Daylight Time is 4 hours behind British Summer Time.
9:00 am09:00 in ADT is 1:00 pm13:00 in BST
ADT to BST call time
Best time for a conference call or a meeting is between 9am-1pm09:00-13:00 in ADT which corresponds to 1pm-5pm13:00-17:00 in BST
9:00 am09:00 Atlantic Daylight Time (ADT). Offset UTC -3:00 hours
1:00 pm13:00 British Summer Time (BST). Offset UTC +1:00 hour
9:00 am09:00 ADT / 1:00 pm13:00 BST
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.
| ADT | BST |
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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
Today the lighter areas are on UTC−3 (ADT).
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).
End: 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.
Start: 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.
AST representations, usage and related time zones
- -04 - basic short
- -0400 - basic
- -04:00 - extended
- -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.
- Quebec - Military abbreviation for AST
- Q - short form of 'Quebec'
- 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
- Atlantic Standard Time - UTC -4
- Arabia Standard Time - UTC +3
- 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
British Summer Time
Offset: BST is 1 hour ahead of Greenwich Mean Time (GMT).
Countries using this time zone: Britain (UK), Guernsey, Isle of Man, Jersey
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.
Today all shaded areas are on BST.
Daylight Saving: British Summer Time (BST) is a daylight saving/summer time zone. During winter, some places set clocks back one hour and observe Greenwich Mean Time (GMT).
Start: British Summer Time (BST) started on Sunday, March 29, 2026 at 1:00 am01:00 local time and clocks were set one hour forward to Sunday, March 29, 2026, 2:00 am02:00. Daylight saving starts annually on the last Sunday of March.
End: British Summer Time (BST) ends on Sunday, October 25, 2026 at 2:00 am02:00 local time and clocks are set one hour back to Sunday, October 25, 2026, 1:00 am01:00 local standard time instead. Daylight saving ends annually on the last Sunday of October.
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