Current Time in London
United Kingdom — Europe/London
About Time in London
London operates on Greenwich Mean Time (IANA: Europe/London). During standard time, this is GMT at UTC+0 — the baseline from which all other time zones are measured. From the last Sunday of March to the last Sunday of October, clocks move forward to British Summer Time (BST) at UTC+1. The changeover occurs at 1:00 AM GMT.
London's position at UTC+0 makes it the natural reference point for global time calculations. It is 5 hours ahead of New York during EST, 9 hours behind Tokyo, and 11 hours behind Sydney during Australian summer. London's time zone, rooted in the Royal Observatory at Greenwich, has been the world's prime meridian since 1884.
GMT/BST profoundly shapes London's role in global finance. The London Stock Exchange opens at 8:00 AM GMT, catching the tail end of the Asian trading day and operating for several hours before New York opens. This 'time zone sandwich' means London-based traders and financial professionals have an overlap window with virtually every major market in the world during their workday, which is a key reason the City of London remains one of the world's top financial centers.
Time Facts
The Royal Observatory in Greenwich, London, is the origin of Greenwich Mean Time and the prime meridian (0 degrees longitude) — visitors can stand with one foot in the Eastern Hemisphere and one in the Western.
Big Ben's clock (officially the Great Clock of the Palace of Westminster) has been keeping time since 1859 and is accurate to within two seconds per week, adjusted by adding or removing old penny coins from the pendulum.
London's Heathrow Airport, the world's busiest international airport, operates in a time zone that allows same-day connections to every inhabited continent — landing in the morning from Asia and departing in the afternoon for the Americas.
The BBC World Service has broadcast the Greenwich Time Signal (the 'pips') at the top of every hour since 1924, synchronizing clocks across the British Empire and later the world.
Business Hours
Standard business hours in London are 9:00 AM to 5:30 PM GMT (09:00-17:30 UTC during GMT, 08:00-16:30 UTC during BST).