Convert Greenwich Mean Time to Atlantic Daylight Time - Quick & Accurate
Updates live every second
Hover over any hour to see corresponding time in both zones
To schedule a meeting between GMT and ADT:
Pro Tip: Schedule calls during the overlap window for optimal convenience for both time zones
| GMT Time | ADT Time | Context |
|---|---|---|
| 12:00 AM | 08:00 PM | Midnight GMT |
| 01:00 AM | 09:00 PM | Late Night |
| 02:00 AM | 10:00 PM | Late Night |
| 03:00 AM | 11:00 PM | Late Night |
| 04:00 AM | 12:00 AM | Late Night |
| 05:00 AM | 01:00 AM | Late Night |
| 06:00 AM | 02:00 AM | Early Morning GMT |
| 07:00 AM | 03:00 AM | Night Time |
| 08:00 AM | 04:00 AM | Night Time |
| 09:00 AM | 05:00 AM | Work Starts GMT |
| 10:00 AM | 06:00 AM | Night Time |
| 11:00 AM | 07:00 AM | Night Time |
London
Europe/London
Halifax
America/Halifax
ADT (Atlantic Daylight Time) is 4 hours behind GMT (Greenwich Mean Time). This means when it's 12:00 PM in London (GMT), it's 8:00 AM in Halifax (ADT).
The best time to call from GMT to ADT is during overlapping business hours. For GMT callers, schedule between 12:00 PM - 5:00 PM GMT to ensure both parties are within standard business hours.
The time difference may change during daylight saving transitions if one region observes DST while the other doesn't. Greenwich Mean Time (UTC+0 (GMT) / UTC+1 (BST)) and Atlantic Daylight Time (UTC-3) may have different DST schedules.
GMT includes cities like London. ADT includes cities like Halifax. Both time zones cover important business and cultural centers.
In 2025, DST in North America starts on March 9 at 2:00 AM and ends on November 2 at 2:00 AM. Other regions may have different DST schedules or not observe DST at all.