BST to AST Converter
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Quick answers
Selected conversion
12:00 pm12:00 GMT (UTC+0), Nov 10, 2026 = 8:00 am08:00 AST (UTC-4), Nov 10, 2026
GMT is 4 hours ahead of AST.
BST and AST examples
These examples always use BST (UTC+1) and AST (UTC-4). They stay the same when you change the date or time above. The selected conversion may differ when daylight saving time applies.
BST is 5 hours ahead of AST.
How the time difference changes
For most of the year, BST is 4 hours ahead of ADT. From Nov 1, 2026 to Mar 14, 2027, and from Nov 7, 2027 to Mar 12, 2028, GMT is 4 hours ahead of AST. From Mar 14 to Mar 28, 2027, and from Oct 31 to Nov 7, 2027, GMT is 3 hours ahead of ADT.
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 AST time, including current local time, UTC offsets, time difference, daylight saving changes, working hours, and shareable meeting times.
Time Difference
Greenwich Mean Time is 4 hours ahead of Atlantic Standard Time.
12:00 pm12:00 in GMT is 8:00 am08:00 in AST
GMT to AST call time
Best time for a conference call or a meeting is between 1pm-6pm13:00-18:00 in GMT which corresponds to 9am-2pm09:00-14:00 in AST.
12:00 pm12:00 Greenwich Mean Time (GMT). Offset UTC 0:00 hours
8:00 am08:00 Atlantic Standard Time (AST). Offset UTC -4:00 hours
12:00 pm12:00 GMT / 8:00 am08:00 AST
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 Standard Time
Offset: AST is 4 hours behind Greenwich Mean Time (GMT).
Countries using this time zone: Anguilla, Antigua and Barbuda, Aruba, Barbados, Bermuda, British Virgin Islands, Canada, Caribbean Netherlands, Curaçao, Dominica, Dominican Republic, Greenland, Grenada, Guadeloupe, Martinique, Montserrat, Puerto Rico, Saint Barthélemy, Saint Kitts and Nevis, Saint Lucia, Saint Martin, Saint Vincent and the Grenadines, Sint Maarten, Trinidad and Tobago, US Virgin Islands
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 all shaded areas are on AST.
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).
Start: Atlantic Standard Time (AST) started on Sunday, November 1, 2026 at 2:00 am02:00 local time and clocks were set one hour back to Sunday, November 1, 2026, 1:00 am01:00. Standard time starts annually on the first Sunday of November.
End: Atlantic Standard Time (AST) ends on Sunday, March 14, 2027 at 2:00 am02:00 local time and clocks are set one hour forward to Sunday, March 14, 2027, 3:00 am03:00 local daylight time instead. Standard time ends annually on the second Sunday of March.
See Canada daylight saving time and upcoming clock changes worldwide.
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
- GYT - Guyana Time
- HLV - Hora Legal de Venezuela
- Q - Quebec Time Zone
- VET - Venezuelan Standard Time