What is AST in BST?
British Time is 4 hours ahead
Convert a time
GMT — British Time
8:00 am
GMT, Sat
- Time in Halifax
- 4:28:43 AM
- Time in London
- 8:28:43 AM
- Difference
- +4 h
- Next clock change
- March 14, 2027
When the difference changes
Atlantic Time and British Time do not change their clocks on the same dates, so the gap between them is not the same all year. Most converters show only today’s figure. These are the periods ahead:
- Now – March 14, 2027British Time is 4 hours ahead
- March 14, 2027 – March 27, 2027British Time is 3 hours ahead
- March 27, 2027 – October 30, 2027British Time is 4 hours ahead
- October 30, 2027 – November 7, 2027British Time is 3 hours ahead
- November 7, 2027 – onwardsBritish Time is 4 hours ahead
Periods shorter than a day are not listed. Each zone changes at its own local time, so on a date when both move there are a few hours when the gap is briefly something else.
Daylight saving
Atlantic Time
Clocks go forward one hour — 2:00 am becomes 3:00 am local time, and the zone is on ADT after that.
British Time
Clocks go forward one hour — 1:00 am becomes 2:00 am local time, and the zone is on BST after that.
AST to BST conversion table
Every hour of Saturday, November 7, 2026, converted from Atlantic Time to British Time. 4 of the 24 hours fall on a different calendar day in London, which is marked.
- 12:00 am AST
- 4:00 am GMT
- 1:00 am AST
- 5:00 am GMT
- 2:00 am AST
- 6:00 am GMT
- 3:00 am AST
- 7:00 am GMT
- 4:00 am AST
- 8:00 am GMT
- 5:00 am AST
- 9:00 am GMT
- 6:00 am AST
- 10:00 am GMT
- 7:00 am AST
- 11:00 am GMT
- 8:00 am AST
- 12:00 pm GMT
- 9:00 am AST
- 1:00 pm GMT
- 10:00 am AST
- 2:00 pm GMT
- 11:00 am AST
- 3:00 pm GMT
- 12:00 pm AST
- 4:00 pm GMT
- 1:00 pm AST
- 5:00 pm GMT
- 2:00 pm AST
- 6:00 pm GMT
- 3:00 pm AST
- 7:00 pm GMT
- 4:00 pm AST
- 8:00 pm GMT
- 5:00 pm AST
- 9:00 pm GMT
- 6:00 pm AST
- 10:00 pm GMT
- 7:00 pm AST
- 11:00 pm GMT
- 8:00 pm AST
- 12:00 am GMT+1 day
- 9:00 pm AST
- 1:00 am GMT+1 day
- 10:00 pm AST
- 2:00 am GMT+1 day
- 11:00 pm AST
- 3:00 am GMT+1 day
Scheduling between the two
Working hours overlap from 9:00 am to 2:00 pm AST, which is 1:00 pm to 6:00 pm GMT. Anything inside that window falls in the normal working day at both ends.
A note on AST: it can also mean Arabia Standard Time (UTC+3). This page means Atlantic Time.
A note on BST: it can also mean Bangladesh Standard Time (UTC+6). This page means British Summer Time.
Atlantic Time (AST) is used in Nova Scotia, New Brunswick and Puerto Rico
British Time (GMT) is used in the whole United Kingdom. In winter the UK is on GMT; from late March to late October it is on BST, an hour ahead.
Other conversions
- BST to AST
- AST to UTC
- AST to GMT
- AST to EST
- AST to CST
- AST to MST
- AST to PST
- AST to AKST
- AST to HST
- AST to CET
- AST to IST
- AST to CST (China)
- AST to JST
- AST to AEST
- AST to Mexico City
- AST to BRT
- AST to ART
- AST to EET
- AST to WET
- AST to MSK
- AST to TRT
- AST to SAST
- AST to WAT
- AST to EAT
- AST to GST
- AST to PKT
- AST to ICT
- AST to WIB
- AST to SGT
- AST to HKT
- AST to KST
- AST to PHT
- AST to AWST
- AST to ACST
- AST to NZST
- All zones