At 01:00 GMT on Sunday 29 March 2026, every clock in the United Kingdom jumps forward to 02:00. The country has just shed Greenwich Mean Time for British Summer Time. For the next seven months, the UK runs an hour ahead of its winter self. That single hour reshapes trading floors, broadcast schedules, and whether your call from New York connects or cuts dead.
What Is GMT?
GMT is the mean solar time at the Royal Observatory in Greenwich, London, sitting at UTC+0. The UK uses it as civil time during winter, from late October to late March.
For how a 17th-century navigation problem created the world’s first time standard, read Greenwich Mean Time (GMT).
What Is BST?
British Summer Time is the UK’s daylight saving time, running from late March to late October at UTC+1. Clocks move one hour ahead of GMT to shift daylight from early morning to evening.
The full story, from William Willett’s 1907 pamphlet to the current rules, is on British Summer Time (BST).
GMT vs BST: Which Offset Rules When?
| GMT | BST | |
|---|---|---|
| Full name | Greenwich Mean Time | British Summer Time |
| UTC offset | UTC+0 | UTC+1 |
| Active months | Late October to late March | Late March to late October |
| Common label | Winter time | Summer time, daylight saving |
| IANA zone | Europe/London |
Europe/London |
The rule: schedule UK meetings in BST from April through September. Use GMT from November through February. March and October are transition months. Check the exact dates below.
When Do the Clocks Change? GMT ↔ BST Switch Dates
Clocks change on the last Sunday of March and the last Sunday of October, always at 01:00 UTC.
Spring Forward: GMT to BST
Sunday 29 March 2026 at 01:00 GMT. Clocks go forward 60 minutes to 02:00 BST.
Sunday 28 March 2027 at 01:00 GMT. Clocks go forward 60 minutes to 02:00 BST.
Fall Back: BST to GMT
Sunday 25 October 2026 at 02:00 BST. Clocks go back 60 minutes to 01:00 GMT.
Sunday 31 October 2027 at 02:00 BST. Clocks go back 60 minutes to 01:00 GMT.
What Happens on the Night?
The 01:00 UTC trigger lands after pubs close and before most rail services start. On change nights, trains scheduled at the shift point hold or adjust. The London Underground Night Tube runs through the change with operational adjustments. If you are booking travel across the autumn switch, confirm whether your 01:30 departure is before or after the clocks fall back.
Why Your July Meeting Keeps Failing
Assuming the UK stays on GMT all year. It does not.
International callers set a July meeting at 14:00 GMT. The UK clock reads 15:00 BST. One side sits in an empty conference room. Some organisations label summer timetables "GMT+1". Wrong. The correct name is British Summer Time. BBC World Service prints "GMT" year-round. They mean UTC. A July schedule showing "14:00 GMT" translates to 15:00 BST in the UK.
How to Fix It
If the date falls between the last Sunday of March and the last Sunday of October, add one hour to any GMT time you see. Send calendar invites in Europe/London and let the software handle the offset. For a July call with New York, write "London 14:00 BST / New York 09:00 EDT." Never write "14:00 GMT" for a summer meeting.
GMT vs BST vs UTC: Three Terms, One Reference Point
- UTC (Coordinated Universal Time): the atomic constant. It never shifts for seasons. The reference.
- GMT: a time zone equal to UTC+0. The UK uses it in winter.
- BST: a time zone equal to UTC+1. The UK uses it in summer.
So BST = UTC+1. GMT = UTC+0. UTC is the fixed spine; GMT and BST are the UK’s seasonal offsets hung from it.
For the technical distinction between the solar and atomic standards, read GMT vs UTC. For how the whole UK system fits together, see UK Time Zone Explained: GMT, BST, and Europe/London.
GMT vs BST: Which One Do You Need Right Now?
| Your situation | Use |
|---|---|
| Scheduling a January meeting in London | GMT (UTC+0) |
| Booking an August flight to the UK | BST (UTC+1) |
| Watching a live event in October | Check if before or after the 25th |
| Reading a BBC World Service schedule in July | Add one hour for BST |
| Configuring software for UK time | IANA zone Europe/London |
| Calling Dubai from London in January | London is 4 hours behind (GMT) |
| Calling Dubai from London in July | London is 3 hours behind (BST) |
| Calling New York from London, any season | London is 5 hours ahead |
Does the UK change clocks every year?
Yes. The UK has observed daylight saving since the Summer Time Act 1916. The current schedule (last Sunday of March to last Sunday of October) has held since the Summer Time Act 1972. As of October 2026, Parliament has no confirmed plan to stop. The British Sleep Society published a position statement in October 2024 recommending permanent GMT on circadian health grounds. No legislation has followed.
What is the time difference between London and New York?
London is 5 hours ahead of New York in both winter and summer. In January, London runs on GMT (UTC+0) against New York’s EST (UTC-5). In July, London runs on BST (UTC+1) against New York’s EDT (UTC-4). The gap stays fixed because both cities shift their clocks on similar schedules.
What is the time difference between London and Dubai?
In winter (GMT), London is 4 hours behind Dubai (UTC+4). In summer (BST), London is 3 hours behind. Dubai does not observe daylight saving time.
Is GMT the same as UTC?
For everyday civil time, yes. Both share the UTC+0 offset. Technically, GMT is a solar-based time zone and UTC is an atomic standard. The UK uses them interchangeably in winter.
Do Scotland, Wales, and Northern Ireland use the same time as England?
Yes. All four nations use the single IANA zone Europe/London. Time is a reserved matter for Westminster. Devolved administrations have no separate time zone powers. The solar difference between the UK’s westernmost point (Belleek, County Fermanagh) and easternmost (Lowestoft, Suffolk) is roughly 32 minutes. The clocks show the same hour regardless.