BST to AST Converter
AST is 4 hours behind GMT. 9:00 AM GMT = 5:00 AM AST.
AST is 4 hours behind GMT at the moment. To convert BST to AST, subtract 4 hours from the BST time: 9:00 AM GMT = 5:00 AM AST.
BST (British Time) is used in United Kingdom from late March to late October. AST (Atlantic Time) is used in Nova Scotia, New Brunswick, PEI; Puerto Rico and the Eastern Caribbean (all year).
BST here means British Summer Time, not Bangladesh Standard Time. AST here is Atlantic Standard Time, not Arabia Standard Time. BST (British Summer Time) is not in force right now: United Kingdom from late March to late October is currently on GMT. This page uses whichever name applies on the date you pick, so the numbers below say GMT.
BST to AST time conversion table
BST to AST on 6 Nov 2026. Today's date. Highlighted rows are 9 AM–5 PM in both places.
| BST | AST | Day |
|---|---|---|
| 12:00 AM GMT | 8:00 PM AST | previous day |
| 1:00 AM GMT | 9:00 PM AST | previous day |
| 2:00 AM GMT | 10:00 PM AST | previous day |
| 3:00 AM GMT | 11:00 PM AST | previous day |
| 4:00 AM GMT | 12:00 AM AST | night |
| 5:00 AM GMT | 1:00 AM AST | night |
| 6:00 AM GMT | 2:00 AM AST | night |
| 7:00 AM GMT | 3:00 AM AST | night |
| 8:00 AM GMT | 4:00 AM AST | night |
| 9:00 AM GMT | 5:00 AM AST | night |
| 10:00 AM GMT | 6:00 AM AST | — |
| 11:00 AM GMT | 7:00 AM AST | — |
| 12:00 PM GMT | 8:00 AM AST | — |
| 1:00 PM GMT | 9:00 AM AST | work hours |
| 2:00 PM GMT | 10:00 AM AST | work hours |
| 3:00 PM GMT | 11:00 AM AST | work hours |
| 4:00 PM GMT | 12:00 PM AST | work hours |
| 5:00 PM GMT | 1:00 PM AST | — |
| 6:00 PM GMT | 2:00 PM AST | — |
| 7:00 PM GMT | 3:00 PM AST | — |
| 8:00 PM GMT | 4:00 PM AST | — |
| 9:00 PM GMT | 5:00 PM AST | — |
| 10:00 PM GMT | 6:00 PM AST | — |
| 11:00 PM GMT | 7:00 PM AST | — |
- Work rows — 9 AM–5 PM in both places
- Night in the destination (10 PM–6 AM)
How to convert BST to AST
Subtract 4 hours from the BST time to get AST.
Example: 9:00 AM GMT = 5:00 AM AST.
Across midnight: 1:00 AM GMT = 9:00 PM AST (previous day). The date changes, so always check the day as well as the hour.
Time difference between BST and AST
The time difference between BST and AST is not the same all year, because the two sides change for daylight saving time on different dates. In 2026 it works out like this:
- 1 Jan 2026 – 7 Mar 2026: AST is 4 hours behind of BST.
- 8 Mar 2026 – 28 Mar 2026: AST is 3 hours behind of BST.
- 29 Mar 2026 – 24 Oct 2026: AST is 4 hours behind of BST.
- 25 Oct 2026 – 31 Oct 2026: AST is 3 hours behind of BST.
- 1 Nov 2026 – 31 Dec 2026: AST is 4 hours behind of BST.
BST and AST during daylight saving time
- BST next changes on 28 Mar 2027: clocks go forward one hour at 00:59 local time, from GMT (UTC+0) to BST (UTC+1).
- AST next changes on 14 Mar 2027: clocks go forward one hour at 01:59 local time, from AST (UTC−4) to ADT (UTC−3).
Best time for a meeting between BST and AST
BST and AST share 4 hours of the 9 AM–5 PM working day. Any time between 1:00 PM and 5:00 PM GMT lands between 9:00 AM and 1:00 PM AST, inside working hours for both.
BST to AST FAQ
What is the time difference between BST and AST?
Right now AST is 4 hours behind GMT. The gap changes 5 times in 2026 because the two sides switch to daylight saving time on different dates.
What is 9 AM BST in AST?
9:00 AM GMT is 5:00 AM AST.
What is 12 PM (noon) BST in AST?
12:00 PM GMT is 8:00 AM AST.
Is AST ahead of or behind BST?
AST is 4 hours behind GMT, so it is earlier in AST than in BST.
Does BST change for daylight saving time?
Yes. BST next changes on 28 Mar 2027, when clocks go forward one hour from GMT to BST.
Does AST change for daylight saving time?
Yes. AST next changes on 14 Mar 2027, when clocks go forward one hour from AST to ADT.
What is the best time for a meeting between BST and AST?
BST and AST share 4 hours of the 9 AM–5 PM working day. Any time between 1:00 PM and 5:00 PM GMT lands between 9:00 AM and 1:00 PM AST, inside working hours for both.
Related conversions
Convert AST to BST
Convert BST to other time zones
Convert other time zones to AST
Learn more
Updated 6 November 2026. Time zone data: IANA tz database.