Current Time in London

London uses two timezone labels across the year. GMT (Greenwich Mean Time, UTC+0) is active from the last Sunday in October to the last Sunday in March, the winter months. BST (British Summer Time, UTC+1) is active from late March to late October, when the UK observes Daylight Saving Time.

The name GMT comes from the Royal Observatory in Greenwich, London, established as the prime meridian (0° longitude) at the 1884 International Meridian Conference. For over 80 years, GMT was the world's primary time standard. In 1972, UTC (Coordinated Universal Time) formally replaced GMT as the international standard, maintained by atomic clocks rather than solar observation. In everyday use, GMT and UTC are treated as identical at UTC+0.

One practical detail that catches people off guard: the UK and the US switch for Daylight Saving Time on different dates. The US springs forward on the second Sunday in March; the UK doesn't switch until the last Sunday in March, two to three weeks later. During that window, the London to New York time difference is 4 hours instead of the usual 5. The same applies in autumn: the UK falls back in late October, the US in early November, creating a brief period where the gap is 4 hours. For software, the zone identifier is Europe/London, which covers the whole of the UK.