Clocks
British Summer Time, GMT and UTC
Enter a date and a time: whether the UK is on GMT or BST that day, and the same moment in UTC.
UK time from GMT or UTC on any date
UK time
13:00 BST
| Offset from UTC | +1 hour |
| Summer time that year | 28 March 2027 to 31 October 2027 |
British Summer Time, or BST, is the time the UK keeps in summer: one hour ahead of Greenwich Mean Time, so UTC plus one hour. In 2027 it runs from 1am GMT on Sunday, 28 March 2027 to 1am GMT on Sunday, 31 October 2027, 217 days in all. The rest of the year the UK is on GMT, which for everyday purposes is the same as UTC, the world's reference time. The period is set by the Summer Time Order 2002 under the Summer Time Act 1972: from the last Sunday in March to the last Sunday in October, the same dates as the European Union. Summer time was first introduced in 1916, after a campaign by the builder William Willett, to make better use of daylight. The UK tried staying on GMT plus one all year round from 1968 to 1971, and dropped the experiment largely because of dark winter mornings in Scotland and the north.
Clock changes in a given year
Clocks go back
31 October 2027, 2am
| Clocks go forward | 28 March 2027, 1am |
| Days on British Summer Time | 217 |
| Days on GMT that year | 148 |
Rules and dates checked by Radif Partners · Editorial policy · Method
BST periods, 2026 to 2032
| Year | BST starts (1am GMT) | BST ends (1am GMT) | Days on BST |
|---|---|---|---|
| 2026 | 29 March 2026 | 25 October 2026 | 210 |
| 2027 | 28 March 2027 | 31 October 2027 | 217 |
| 2028 | 26 March 2028 | 29 October 2028 | 217 |
| 2029 | 25 March 2029 | 28 October 2029 | 217 |
| 2030 | 31 March 2030 | 27 October 2030 | 210 |
| 2031 | 30 March 2031 | 26 October 2031 | 210 |
| 2032 | 28 March 2032 | 31 October 2032 | 217 |
GMT, BST and UTC
Three abbreviations cover all UK time. GMT is the winter time. BST is the summer time, GMT plus one hour. UTC is the international reference used by aviation, computer systems and science, and in winter it matches UK time exactly. A meeting set for 14:00 UTC in July is therefore at 3pm in London, while one set for 14:00 UTC in January is at 2pm. Other time zones are usually described against UTC: New York is UTC minus five in winter and minus four in summer, but the United States changes its clocks on different dates from Europe, so for a few weeks in March and late October to early November the gap between London and New York is four hours instead of five.
A century of changing the clocks
William Willett, a London builder, argued from 1907 that clocks should be put forward in summer so that people would make better use of daylight. He died in 1915. The Summer Time Act 1916 introduced the idea in wartime, to save coal, and it was kept after the war. In the Second World War the country used double summer time, two hours ahead of GMT, in the summer months and one hour ahead in winter. The current law is the Summer Time Act 1972, with the dates set by the Summer Time Order 2002 to match the EU directive of 2000.
The British Standard Time experiment of 1968 to 1971 kept GMT plus one all year. Road accidents in the darker mornings and the gain in lighter evenings were argued over for years; Parliament voted to return to the seasonal change in 1971. Bills to try it again, sometimes called Lighter Later Evenings, were debated in the 2010s and did not become law.
Using the converter
Choose a date and a time, and say whether the time you have is UTC or UK local time. The converter applies the 2002 rule for that year and gives the other one. On the night the clocks go forward, the times from 1am to 1.59am do not exist in the UK; on the night they go back, the times from 1am to 1.59am happen twice, once in BST and once in GMT. The converter flags both cases. The clocks go forward and clocks go back pages count down to the next changes.
Mobile phones and computers set to the London time zone change by themselves, using the same rule built into their software.