The listing for Big Ben Blocks says the Daily Challenge changes at midnight UK time. “UK time” is not one fixed offset from the world's clocks. It is Greenwich Mean Time for part of the year and British Summer Time for the rest, and the switch between them happens this weekend. Here is how the two fit together, what the change does to the hour of midnight, and how to turn it into your own clock.
GMT, BST and UTC
Three labels do most of the work:
- UTC is the world reference time. It never changes for daylight saving.
- GMT is UTC+0. The UK uses it in winter.
- BST, British Summer Time, is UTC+1. The UK uses it in summer, so its clocks run one hour ahead of GMT.
So 00:00 UK time is 00:00 UTC in winter, and 23:00 UTC the evening before in summer. Everything else in this post follows from that one-hour difference.
The two changes in a year
The rule is tied to Sundays, so the dates move each year:
- Clocks go forward on the last Sunday of March, at 01:00 GMT, which becomes 02:00 BST.
- Clocks go back on the last Sunday of October, at 02:00 BST, which becomes 01:00 GMT.
Today is Friday 23 October 2026. The last Sunday of October is 25 October, so the clocks go back this Sunday. The last Sunday of March was 29 March 2026 and will be 28 March 2027. The next Sunday, 1 November, is already in November.
The usual memory aid is “spring forward, fall back”.
What happens around midnight on Sunday
The change happens at 02:00, after midnight, so Sunday starts normally. UK midnight at the start of Saturday 24 October and at the start of Sunday 25 October are both in BST, at 23:00 UTC the evening before. Monday 26 October starts in GMT, at 00:00 UTC.
That makes Sunday 25 October a 25-hour day in the UK, from 23:00 UTC on Saturday to 00:00 UTC on Monday. Sunday 28 March 2027 goes the other way: it runs from 00:00 UTC to 23:00 UTC, which is 23 hours. So the midnight that starts Monday 26 October comes 25 hours after the one that starts Sunday, and 24 hours after the midnight before on every other day this week.
In a place that does not change its clocks, UK midnight arrives one hour later on the clock after the UK goes back: 03:00 becomes 04:00 in Dubai, and 08:00 becomes 09:00 in Tokyo.
UK midnight in other zones
Take 00:00 UK time as the moment the Daily Challenge changes. Here is when that lands on a clock elsewhere, using the standard time zone rules, in mid-July (BST) and mid-January (GMT):
- Paris and Berlin: 01:00 in July and 01:00 in January. Central Europe moves its clocks on the same Sunday as the UK, so the gap stays at one hour.
- Dubai (UTC+4, no change): 03:00 in July, 04:00 in January.
- Mumbai and Delhi (UTC+5:30, no change): 04:30 in July, 05:30 in January.
- Tokyo (UTC+9, no change): 08:00 in July, 09:00 in January.
- Sydney: 09:00 in July (UTC+10) and 11:00 in January (UTC+11), because Sydney moves its clocks forward in October and back in April.
- New York: 19:00 the previous evening in both July (UTC−4) and January (UTC−5), because New York also changes its clocks.
- Los Angeles: 16:00 the previous afternoon in both January (UTC−8) and July (UTC−7), for the same reason.
The chart shows how far ahead of UK clocks each of the eastern cities is in January, when the UK is on GMT.
The weeks when the gaps don't match
Countries do not all change on the same day. The United States ends daylight saving on the first Sunday of November, which is 1 November 2026, a week after the UK. For the seven days from 25 October, New York is still on UTC−4 while the UK is on UTC+0, so UK midnight falls at 20:00 the evening before. From 1 November it is 19:00 again. In spring the mismatch runs the other way and lasts longer: the US moves on the second Sunday of March (14 March 2027) and the UK on 28 March, so for two weeks the gap is four hours rather than five.
If you play from North America, that is the reason the “usual” evening of the reset can shift by an hour for a short stretch twice a year.
Working out your own time
Three steps are enough:
- Find out whether the UK is on GMT (UTC+0) or BST (UTC+1) on that date. Between the last Sundays of March and October it is BST.
- Subtract that offset from 00:00 to get the UTC time. In BST, 00:00 is 23:00 UTC the day before.
- Add your own zone's current offset to the UTC time.
For Sydney in January: 00:00 GMT is 00:00 UTC, and adding 11 hours gives 11:00. For Los Angeles in July: 00:00 BST is 23:00 UTC, and 23:00 − 7 hours is 16:00.
The listing says the Daily Challenge changes at midnight UK time and gives nothing further on how the clock change is handled, so use the steps above to work out when that stated time falls on your own clock.
Why it matters for a daily puzzle
A daily puzzle is easiest to plan if you know which hour on your own clock starts the next one. The Daily Challenge keeps undo, hints, rotate and bomb switched off, as the post on Time Attack notes for both of those modes. Knowing when the day turns over lets you decide whether to play before or after it. This week that means a one-hour shift in most places that do not change their clocks, and none in Paris or Berlin.
Big Ben Blocks: Block Puzzle offers untimed Classic play or a three-minute Time Attack, and the Daily Challenge changes at midnight UK time. Reach the crown score, build a streak and follow your progress on the monthly calendar. It plays offline with no ads and no in-app purchases, and the coins you earn have no cash value.