Europe & Africa · UTC+0
Greenwich Mean Time
GMT
UTC+0
UK observes BST (UTC+1) from late March to late October
Europe & Africa
UTC+1 (BST in UK)
Greenwich Mean Time (GMT) is the world's time standard at UTC+0. It is the baseline from which all other time zones are calculated and is used across West Africa and Western Europe in winter.
Use our Time Zone Converter to instantly convert GMT to any other time zone worldwide. You can also add Europe & Africa cities to the World Clock to track multiple time zones simultaneously.
UK observes BST (UTC+1) from late March to late October. For a full list of DST changes worldwide, see our DST Changes page.
Greenwich Mean Time (GMT) is the time at the Royal Observatory in Greenwich, London, and serves as the baseline for all world time zones. It is at UTC+0 — no offset from Coordinated Universal Time. Unlike UTC, which is a scientific standard, GMT is a time zone used by several countries and is the reference point from which all other time zones are measured as positive or negative offsets.
GMT is used year-round in the United Kingdom during winter (when BST is not in effect), Iceland, Ghana, Senegal, Ivory Coast, and several other West African and Atlantic nations. It is also widely used in aviation, maritime navigation, and international broadcasting as a neutral reference time.
GMT and UTC are almost identical in practice — both represent time at the zero meridian. The key difference is that UTC is a precise scientific standard maintained by atomic clocks, while GMT is a time zone. For everyday scheduling, they can be treated as the same thing.
No — the UK observes British Summer Time (BST) from late March to late October, during which clocks are set to UTC+1. The rest of the year the UK uses GMT (UTC+0).
GMT is the baseline — it is neither ahead nor behind itself. Every other time zone is expressed as GMT+ or GMT−. For example, EST is GMT−5, EAT is GMT+3, and IST (India) is GMT+5:30.
The name comes from the Royal Observatory in Greenwich, London, which was established as the prime meridian (0° longitude) at the International Meridian Conference in 1884. "Mean Time" refers to the average (mean) solar time at that location — averaging out the slight variations in the Sun's position throughout the year.