GMT to ADT Time Converter

When it is 9:00 AM GMT, it is 5:00 AM ADT. Atlantic Daylight Time (ADT, UTC-3) is 3 hours behind Greenwich Mean Time (GMT, UTC+0). Your working-hours overlap window is 12:00 PM–5:00 PM GMT (9:00 AM–2:00 PM ADT).

GMT to ADT Conversion Table

Major Cities Using GMT and ADT

Greenwich Mean Time (GMT): London, Manchester, Dublin, Edinburgh.

Atlantic Daylight Time (ADT): Halifax, Saint John, Moncton.

How many hours between GMT and ADT?

GMT is UTC+0 and ADT is UTC-3, a difference of 3 hours. ADT is behind GMT. This difference can shift by an hour in either direction during Daylight Saving Time transitions — if one zone observes DST and the other doesn't, the offset narrows or widens for part of the year.

Business Hours Overlap: GMT ↔ ADT

Assuming a 9:00 AM – 5:00 PM workday on each side, your working-hours overlap window is 12:00 pm–5:00 pm gmt (9:00 am–2:00 pm adt). To visualize this instantly for any pair of cities, use the visual meeting planner or the timezone overlap finder — both highlight the green overlap window on a live timeline.

Does GMT observe Daylight Saving Time?

Greenwich Mean Time (GMT) is based on the Europe/London IANA timezone. DST observance depends on the jurisdiction — for example, most of the continental US switches between standard and daylight time, while India, Japan, and most of Southeast Asia do not observe DST at all. WorldClock.lol uses the authoritative IANA timezone database, so every conversion automatically accounts for the correct DST rules on the date you're converting.

When is 9 AM GMT in ADT?

When it is 9:00 AM in Greenwich Mean Time (GMT, UTC+0), it is 5:00 AM in Atlantic Daylight Time (ADT). For other times of day, scan the conversion table above or drop into the interactive converter to pick an exact minute. The converter handles both standard and daylight variants correctly.

How to Use This GMT to ADT Converter

1. Type or drag any time in the GMT input above — the ADT equivalent updates instantly.
2. Check the day indicator. When the converted time crosses midnight, the tool shows +1 day or −1 day so you don't book a meeting on the wrong date.
3. Copy the shareable URL to send the specific conversion to a colleague — the link preserves your exact selection.
4. Switch directions by swapping the input zones, or open ADT to GMT for the reverse.

Related GMT Converters

• GMT to EST
• GMT to PST
• GMT to UTC
• GMT to IST
• GMT to JST
• GMT to CET

Related ADT Converters

• EST to ADT
• PST to ADT
• UTC to ADT
• IST to ADT
• JST to ADT
• CET to ADT

More Time Tools

• All Time Zone Converters — browse every supported pair
• About GMT (Greenwich Mean Time) — current time, cities, DST rules
• About ADT (Atlantic Daylight Time) — current time, cities, DST rules
• Meeting Planner — find the best time for a multi-city meeting
• Best Time to Call — optimal calling windows between any two cities
• UTC Time Now — the reference point for every conversion
• DST Schedule 2026 — every daylight-saving transition this year