What is daylight saving time?
Daylight saving time is the practice of moving clocks forward for part of the year so evenings have more daylight. In the UK, this period is called British Summer Time.
Daylight saving time is when clocks are moved forward during part of the year to shift more daylight into the evening. In the UK, the daylight saving period is called British Summer Time, or BST.
When the UK is on BST, local UK time is one hour ahead of GMT. When the clocks go back in autumn, the UK returns to GMT.
How daylight saving time works in the UK
In the UK, the clocks normally go forward by one hour at 1am on the last Sunday in March. They go back by one hour at 2am on the last Sunday in October.
| Period | Common UK label | UTC offset |
|---|---|---|
| Winter clock time | GMT | UTC+0 |
| Summer clock time | BST | UTC+1 |
For 2026, GOV.UK lists the UK clock change dates as 29 March for clocks going forward and 25 October for clocks going back.
Why daylight saving time matters
Daylight saving time matters because it changes the offset between the UK and other time zones during part of the year. A meeting that is “9am UK time” may convert differently in winter and summer.
Do not rely on a memorised time difference for international meetings. Convert the exact date and time, because daylight saving changes can alter the result.
This is especially important for online meetings, travel, deadlines, launches, remote work and countdowns.
Daylight saving, GMT, BST and UTC
UTC is the global reference standard used for precise time conversion. GMT is the familiar UK winter-time label. BST is the UK summer-time label used while daylight saving time is active.
Winter UK time: GMT = UTC+0
Summer UK time: BST = UTC+1
Example: 09:00 UK local time in summer is 08:00 UTC.If a page says “GMT” for a summer event, check whether it really means GMT or whether it means current UK local time.
Daylight saving time examples
Here are simple examples of why the clock-change period matters:
Daylight saving time FAQs
What does daylight saving time mean?
It means clocks are moved forward for part of the year so more daylight falls in the evening. In the UK, this summer period is called British Summer Time.
Is daylight saving time the same as BST?
In UK everyday use, BST is the name for the daylight saving period. During BST, UK local time is normally one hour ahead of GMT.
When do UK clocks change?
The UK clocks normally go forward on the last Sunday in March and back on the last Sunday in October. Always check the exact year if the date matters.
Does daylight saving affect time-zone conversion?
Yes. It can change the time difference between places, so convert the exact date and time rather than using a fixed offset from memory.
Notes
- GOV.UK says UK clocks go forward by one hour at 1am on the last Sunday in March and back by one hour at 2am on the last Sunday in October.
- For 2026, GOV.UK lists 29 March as the forward clock-change date and 25 October as the back clock-change date.
- For meetings, travel plans and deadlines, use the time zone converter with the exact date rather than relying on memory.