Reference offset
GMT is commonly associated with UTC+0. The live clock shows the current regional offset separately.
Time-zone reference
Greenwich Mean Time
GMT is the historical mean-solar reference associated with Greenwich and still used as a common comparison point.
Enable JavaScript for the live regional clock.
Enable JavaScript for the live regional clock.
GMT and the London clock
GMT is a zero-offset reference associated with Greenwich. For ordinary clock comparison it has the same reading as UTC. This page shows the fixed GMT reference, not London’s seasonal local clock.
Use Europe/London for an appointment that should follow London time throughout the year. Use a fixed UTC or GMT reference only when you intend to hold the same universal hour regardless of seasonal local changes.
Conversion example
At 12:00 GMT, a UTC+02:00 clock reads 14:00. If London is using a summer offset, its local hour will differ from the GMT clock shown here.
A common scheduling mistake
“GMT” and “UK local time” are not interchangeable all year. Check the London city page for its current regional clock.
Regional rules: IANA Time Zone Database Our calculation methods
What this abbreviation usually means
This page clarifies where GMT overlaps with UTC and where everyday usage starts to blur the distinction.
GMT conversion chart
Each hour of GMT (UTC+0) converted to other common standard-time abbreviations. “+1” and “−1” mark the next or previous calendar day.
| GMT | PST | EST | CET | IST | JST | AEST |
|---|---|---|---|---|---|---|
| 00:00 | 16:00−1 | 19:00−1 | 01:00 | 05:30 | 09:00 | 10:00 |
| 01:00 | 17:00−1 | 20:00−1 | 02:00 | 06:30 | 10:00 | 11:00 |
| 02:00 | 18:00−1 | 21:00−1 | 03:00 | 07:30 | 11:00 | 12:00 |
| 03:00 | 19:00−1 | 22:00−1 | 04:00 | 08:30 | 12:00 | 13:00 |
| 04:00 | 20:00−1 | 23:00−1 | 05:00 | 09:30 | 13:00 | 14:00 |
| 05:00 | 21:00−1 | 00:00 | 06:00 | 10:30 | 14:00 | 15:00 |
| 06:00 | 22:00−1 | 01:00 | 07:00 | 11:30 | 15:00 | 16:00 |
| 07:00 | 23:00−1 | 02:00 | 08:00 | 12:30 | 16:00 | 17:00 |
| 08:00 | 00:00 | 03:00 | 09:00 | 13:30 | 17:00 | 18:00 |
| 09:00 | 01:00 | 04:00 | 10:00 | 14:30 | 18:00 | 19:00 |
| 10:00 | 02:00 | 05:00 | 11:00 | 15:30 | 19:00 | 20:00 |
| 11:00 | 03:00 | 06:00 | 12:00 | 16:30 | 20:00 | 21:00 |
| 12:00 | 04:00 | 07:00 | 13:00 | 17:30 | 21:00 | 22:00 |
| 13:00 | 05:00 | 08:00 | 14:00 | 18:30 | 22:00 | 23:00 |
| 14:00 | 06:00 | 09:00 | 15:00 | 19:30 | 23:00 | 00:00+1 |
| 15:00 | 07:00 | 10:00 | 16:00 | 20:30 | 00:00+1 | 01:00+1 |
| 16:00 | 08:00 | 11:00 | 17:00 | 21:30 | 01:00+1 | 02:00+1 |
| 17:00 | 09:00 | 12:00 | 18:00 | 22:30 | 02:00+1 | 03:00+1 |
| 18:00 | 10:00 | 13:00 | 19:00 | 23:30 | 03:00+1 | 04:00+1 |
| 19:00 | 11:00 | 14:00 | 20:00 | 00:30+1 | 04:00+1 | 05:00+1 |
| 20:00 | 12:00 | 15:00 | 21:00 | 01:30+1 | 05:00+1 | 06:00+1 |
| 21:00 | 13:00 | 16:00 | 22:00 | 02:30+1 | 06:00+1 | 07:00+1 |
| 22:00 | 14:00 | 17:00 | 23:00 | 03:30+1 | 07:00+1 | 08:00+1 |
| 23:00 | 15:00 | 18:00 | 00:00+1 | 04:30+1 | 08:00+1 | 09:00+1 |
Where GMT is used
These cities on our world clock use GMT during standard time and BST during daylight saving time:
- London, United Kingdom
- Dublin, Ireland
- Casablanca, Morocco
When GMT and BST switch in London
- : BST begins — at 01:00 local time clocks go forward to 02:00.
- : GMT resumes — at 02:00 local time clocks go back to 01:00.
- : BST begins — at 01:00 local time clocks go forward to 02:00.
- : GMT resumes — at 02:00 local time clocks go back to 01:00.
GMT questions
What is GMT in UTC?
GMT (Greenwich Mean Time) is the same as UTC. To convert GMT to UTC, no adjustment is needed: 12:00 GMT is 12:00 UTC.
Is GMT the same as BST?
No. GMT is the standard-time label and BST is the daylight-saving label for the same region, one hour ahead. Most places that use GMT in winter switch to BST in summer, so a time written as GMT during the summer months is usually a mislabel for BST. When in doubt, name the city or use the IANA zone Europe/London.
Which cities use GMT?
Cities on our world clock that use GMT in standard time include London, Dublin, Casablanca.
Compare GMT with related zones
These are the abbreviations people most often compare against this reference.