What is UTC in AST?
Atlantic Time is 3 hours behind
Coordinated Universal Time is on UTC+0:00 and Atlantic Time is on UTC−3:00 right now. Atlantic Time is on daylight saving, so its clocks read ADT. The gap changes during the year — see below.
- Time in the prime meridian
- 3:47 am
- Time in Halifax
- 12:47 am
- Difference
- −3 h
- Next clock change
- November 1, 2026
Convert a time
ADT — Atlantic Time
12:00 am
Wed
When the difference changes
Coordinated Universal 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:
- Now – November 1, 2026Atlantic Time is 3 hours behind
- November 1, 2026 – March 14, 2027Atlantic Time is 4 hours behind
- March 14, 2027 – onwardsAtlantic Time is 3 hours behind
Periods shorter than a day are not listed: both zones change at 2am in their own local time, so there are a few hours on each transition date when the gap is briefly something else.
Daylight saving
Coordinated Universal Time
Coordinated Universal Time stays on UTC all year, so its offset from UTC never moves.
Atlantic Time
Clocks go back one hour at 2am local time, becoming AST.
UTC to AST conversion table
Every hour of Wednesday, September 23, 2026, converted from Coordinated Universal Time to Atlantic Time. 3 of the 24 hours fall on a different calendar day in Halifax, which is marked.
- 12:00 am UTC
- 9:00 pm ADT−1 day
- 1:00 am UTC
- 10:00 pm ADT−1 day
- 2:00 am UTC
- 11:00 pm ADT−1 day
- 3:00 am UTC
- 12:00 am ADT
- 4:00 am UTC
- 1:00 am ADT
- 5:00 am UTC
- 2:00 am ADT
- 6:00 am UTC
- 3:00 am ADT
- 7:00 am UTC
- 4:00 am ADT
- 8:00 am UTC
- 5:00 am ADT
- 9:00 am UTC
- 6:00 am ADT
- 10:00 am UTC
- 7:00 am ADT
- 11:00 am UTC
- 8:00 am ADT
- 12:00 pm UTC
- 9:00 am ADT
- 1:00 pm UTC
- 10:00 am ADT
- 2:00 pm UTC
- 11:00 am ADT
- 3:00 pm UTC
- 12:00 pm ADT
- 4:00 pm UTC
- 1:00 pm ADT
- 5:00 pm UTC
- 2:00 pm ADT
- 6:00 pm UTC
- 3:00 pm ADT
- 7:00 pm UTC
- 4:00 pm ADT
- 8:00 pm UTC
- 5:00 pm ADT
- 9:00 pm UTC
- 6:00 pm ADT
- 10:00 pm UTC
- 7:00 pm ADT
- 11:00 pm UTC
- 8:00 pm ADT
Scheduling between the two
Working hours overlap from 12:00 pm to 6:00 pm UTC, which is 9:00 am to 3:00 pm ADT. 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.
Coordinated Universal Time (UTC) is used in aviation, computing, and science worldwide. UTC never changes for daylight saving.
Atlantic Time (ADT) is used in Nova Scotia, New Brunswick and Puerto Rico