Greenwich Mean Time (GMT)
Greenwich Time / Zulu Time / UTC
What's the Time in the World's Major Cities?
What's the Time in every country in the World?
Welcome to GreenwichMeanTime.com, the website where we talk about time.
As the seasons turn we prepare to move our clocks forward or back.
Don't forget to check here to catch up with all zone time settings.
Why are we as a species so determined to record time accurately?
Archaeology indicates that humans have used their knowledge of the heavens to measure time for thousands of years. The Sun's annual solstices and equinoxes gave reliable points for mapping the year and the constellations provided
Different societies had their own reasons for dividing the day into hours, and the 24 hour day was used in Europe in the Classical period. Perhaps an important influence on marking the European day was the 6th Century Rule of St
Benedict used in Christian monasteries. Monks gathered for prayer at set times each day.
For 1300 years people used local time so that, wherever you were,the sun was due east at 6 am, due south at noon and due west at 6pm.
Greenwich Observatory initiated standard time when the line of zero longitude was set there. However, it took the need for accurate railway timetables to persuade the rest of the country to adopt Greenwich Mean Time. And it was
only in 1884 that a treaty gave international agreement to using GMT as a standard.
These days we have an internationally agreed measure for time, the Universal Time Clock (UTC) which is fine-tuned by
scientific precision, but here in the UK we still use the old names. In the spring, we move the clocks forward to British Summer time,
and as the autumn leaves are falling we return to GMT.
What is GMT?
The international agreement - UTC
Greenwich Royal Observatory
GMT is an absolute time reference & doesn't change with the seasons.
What is GMT now?
London Time is the same as
Greenwich Mean Time less than half of the year. During Summer Time (Daylight Saving Time), London Time is
GMT+1, also known as
British Summer Time (BST).
What's the current London time now?
Greenwich Mean Time (GMT) was established in 1884 at the
International Meridian Conference, when it was decided to place the Prime Meridian at Greenwich, England.
USA & Canada clocks
on Daylight Saving Time until:
Sunday 1 November 2015 2am local time
EU / UK clocks on
Sunday 29 March 1am GMT