World Timezones

AST-ATLANTIC to GMT Converter

Compare GMT to AST-ATLANTIC instead
Atlantic Time1:35 amFri, Jun 5
Atlantic TimeADT
North America · UTC-3
1:35 amFri, Jun 5
12a
1a
2a
3a
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
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3p
4p
5p
6p
7p
8p
9p
10p
11p
Greenwich Mean TimeBST
Europe · UTC+1
5:35 amFri, Jun 5
4a
5a
6a
7a
8a
9a
10a
11a
12p
1p
2p
3p
4p
5p
6p
7p
8p
9p
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12a
1a
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3a

Offset

The time difference between Atlantic Time and Greenwich Mean Time is 4 hours.

4 hours

Atlantic Time (ADT) is behind Greenwich Mean Time (BST).

ADT: UTC-3

BST: UTC+1

Both zones are currently observing daylight saving time.

When to schedule

Business-hours overlap: 9 AM–1 PM in Atlantic Time (1 PM–5 PM in Greenwich Mean Time).

Both teams are in working hours during this window on weekdays.

Suggested time: 11:00 AM Atlantic Time (3:00 PM Greenwich Mean Time).

This window may shift by an hour during daylight saving time.

Public holidays in 2026

National public holidays can affect availability — a counterpart is likely off work on their own holidays, so it's worth planning meetings and deadlines around them.

Canada

  • New Year's DayThu, Jan 1
  • Good FridayFri, Apr 3
  • Victoria DayMon, May 18
  • Canada DayWed, Jul 1
  • Labour DayMon, Sep 7
  • National Day for Truth and ReconciliationWed, Sep 30
  • ThanksgivingMon, Oct 12
  • Christmas DayFri, Dec 25

United Kingdom

  • Good FridayFri, Apr 3
  • Early May Bank HolidayMon, May 4
  • Spring Bank HolidayMon, May 25
  • Christmas DayFri, Dec 25
  • St. Stephen's DayMon, Dec 28

About these zones

Atlantic Time is also known as AST, or ADT. To call Canada, dial +1.

Greenwich Mean Time is also known as GMT, or BST. To call United Kingdom, dial +44.

Greenwich Mean Time is approximately 2,850 miles northeast of Atlantic Time.

Quick reference

Full 24-hour conversion table — tap any time to open it in the converter.

AST-ATLANTICGMTDay
12:00 am4:00 amSame day
1:00 am5:00 amSame day
2:00 am6:00 amSame day
3:00 am7:00 amSame day
4:00 am8:00 amSame day
5:00 am9:00 amSame day
6:00 am10:00 amSame day
7:00 am11:00 amSame day
8:00 am12:00 pmSame day
9:00 am1:00 pmSame day
10:00 am2:00 pmSame day
11:00 am3:00 pmSame day
12:00 pm4:00 pmSame day
1:00 pm5:00 pmSame day
2:00 pm6:00 pmSame day
3:00 pm7:00 pmSame day
4:00 pm8:00 pmSame day
5:00 pm9:00 pmSame day
6:00 pm10:00 pmSame day
7:00 pm11:00 pmSame day
8:00 pm12:00 am+1 day
9:00 pm1:00 am+1 day
10:00 pm2:00 am+1 day
11:00 pm3:00 am+1 day

Daylight saving time

Both zones observe daylight saving time, but they transition on different dates.

Atlantic Time: next transition on Sunday, November 1, 2026.

Greenwich Mean Time: next transition on Sunday, October 25, 2026.

For approximately 7 days between transitions, the offset between Atlantic Time and Greenwich Mean Time differs from its typical value. Recurring meetings during this window will shift by one hour.

See the daylight saving time page for transition dates across every time zone.

Daylight today

Atlantic Time
Sunrise
5:31 AM
Sunset
8:56 PM
Day length
15h 25m
Greenwich Mean Time
Sunrise
4:47 AM
Sunset
9:13 PM
Day length
16h 25m

Daylight overlap: 11h 41m — 5:31 AM–5:13 PM in Atlantic Time (9:31 AM–9:13 PM in Greenwich Mean Time). Both locations are in daylight during this window.

Cities in these zones

Cities in Atlantic Time

Browse all cities to see the current local time anywhere.

Airports in these zones

Airports in Atlantic Time

  • YHZ

Airports in Greenwich Mean Time

  • LCY
  • LGW
  • LHR
  • LTN
  • STN
  • BHX
  • EMA
  • GLA
  • PIK
  • LBA

Related conversions

Common conversions

What is 9:00 am AST-ATLANTIC in GMT?
9:00 am AST-ATLANTIC is 1:00 pm GMT.
What is 12:00 pm AST-ATLANTIC in GMT?
12:00 pm AST-ATLANTIC is 4:00 pm GMT.
What is 12:30 pm AST-ATLANTIC in GMT?
12:30 pm AST-ATLANTIC is 4:30 pm GMT.
What is 2:00 pm AST-ATLANTIC in GMT?
2:00 pm AST-ATLANTIC is 6:00 pm GMT.
What is 5:00 pm AST-ATLANTIC in GMT?
5:00 pm AST-ATLANTIC is 9:00 pm GMT.
What is 11:30 pm AST-ATLANTIC in GMT?
11:30 pm AST-ATLANTIC is 3:30 am GMT, the next day.