Skip to content
DateAlmanac

What is BST in AST?

Atlantic Time is 4 hours behind

British Time is on UTC+0:00 and Atlantic Time is on UTC−4:00 right now. The gap changes during the year — see below.

Convert a time

AST — Atlantic Time

4:00 am

AST, Sat

Time in London
8:28:46 AM
Time in Halifax
4:28:46 AM
Difference
−4 h
Next clock change
March 14, 2027

When the difference changes

British Time and Atlantic 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:

  1. Now – March 14, 2027Atlantic Time is 4 hours behind
  2. March 14, 2027 – March 28, 2027Atlantic Time is 3 hours behind
  3. March 28, 2027 – October 31, 2027Atlantic Time is 4 hours behind
  4. October 31, 2027 – November 7, 2027Atlantic Time is 3 hours behind
  5. November 7, 2027 – onwardsAtlantic Time is 4 hours behind

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

British Time

Sunday, March 28, 2027

Clocks go forward one hour — 1:00 am becomes 2:00 am local time, and the zone is on BST after that.

Atlantic Time

Sunday, March 14, 2027

Clocks go forward one hour — 2:00 am becomes 3:00 am local time, and the zone is on ADT after that.

BST to AST conversion table

Every hour of Saturday, November 7, 2026, converted from British Time to Atlantic Time. 4 of the 24 hours fall on a different calendar day in Halifax, which is marked.

12:00 am GMT
8:00 pm AST−1 day
1:00 am GMT
9:00 pm AST−1 day
2:00 am GMT
10:00 pm AST−1 day
3:00 am GMT
11:00 pm AST−1 day
4:00 am GMT
12:00 am AST
5:00 am GMT
1:00 am AST
6:00 am GMT
2:00 am AST
7:00 am GMT
3:00 am AST
8:00 am GMT
4:00 am AST
9:00 am GMT
5:00 am AST
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
2:00 pm GMT
10:00 am AST
3:00 pm GMT
11:00 am AST
4:00 pm GMT
12:00 pm AST
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

Scheduling between the two

Working hours overlap from 1:00 pm to 6:00 pm GMT, which is 9:00 am to 2:00 pm AST. Anything inside that window falls in the normal working day at both ends.

A note on BST: it can also mean Bangladesh Standard Time (UTC+6). This page means British Summer Time.

A note on AST: it can also mean Arabia Standard Time (UTC+3). This page means Atlantic Time.

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.

Atlantic Time (AST) is used in Nova Scotia, New Brunswick and Puerto Rico

Other conversions