Time zone · Africa
GMT
Greenwich Mean Time
Greenwich Mean Time (GMT) is the baseline by which every other timezone in the world is measured, anchored at UTC+00:00 across 22 member zones spanning West Africa and Atlantic islands. Most of these zones keep GMT year-round with no clock changes, giving daily life a rare consistency while six of the UK / European members still spring-forward each summer.
Sunday, May 31, 2026
Current offset
UTC+00:00
Standard · GMT
Daylight saving
Not observed
Year-round standard time
IANA zones
16
None observe daylight saving
DST offset
—
No summer variant
About GMT
A fixed, year-round offset.
Greenwich Mean Time (GMT) is the baseline by which every other timezone in the world is measured, anchored at UTC+00:00 across 22 member zones spanning West Africa and Atlantic islands. Most of these zones keep GMT year-round with no clock changes, giving daily life a rare consistency while six of the UK / European members still spring-forward each summer.
IANA zones · the technical identifiers
The 16 zones that resolve to GMT.
For software, always store the IANA identifier — never the abbreviation alone. The database keeps these zones distinct because their rules can, and historically did, diverge.
Cities currently on GMT
The same hour, city by city.
15 cities · all UTC+00:00
Where GMT is used
16 countries.
Same offset · UTC+00:00
Other zones at UTC+00:00 right now.
These named zones share GMT's offset today. When daylight saving rules differ, they drift apart for part of the year.
Frequently asked questions
Common questions about GMT, daylight saving, and how to handle it in software. Can't find what you need? Email [email protected].
- Why is GMT called Greenwich Mean Time?
- It's named after the Royal Observatory in Greenwich, London, where the prime meridian (0° longitude) was established as the world's reference line for time and navigation.
- Do all GMT zones observe daylight saving time?
- No — only the European members like the UK and Ireland switch to UTC+01:00 in summer, while African and Atlantic zones such as Abidjan stay on UTC+00:00 all year.
- How many countries use GMT?
- Over 20 territories and nations fall under GMT, from West African capitals like Accra and Dakar to the British Isles and Iceland.
- Is GMT the same as UTC?
- For everyday scheduling and clocks they are interchangeable, but UTC is the atomic-time standard that replaced GMT for scientific precision.
- What makes GMT special for global coordination?
- It's the zero-offset reference; every other UTC shift is defined as a number of hours ahead of or behind GMT.
- Which well-known cities run on GMT in winter?
- London, Lisbon, Reykjavik, Accra, and Casablanca all sit on UTC+00:00 for part or all of the year.
Free · Developer API
Time, as JSON.
Every IANA time zone with live offsets, DST status, and the countries and cities that use them — clean, dependable JSON. Sign up free and get an API key in seconds.
countries, cities, convert, DST transitions coming next.
Get your free API key →