UTC to GMT / BST Converter
UK time is GMT (UTC+0) in winter and BST (UTC+1) from late March to late October. 12:00 UTC is 12:00 PM on GMT and 1:00 PM on BST.
“BST” on this page means the UTC+1 summer offset only. For the other half of the year the UK is on GMT, so both columns are shown in every table.
UTC to GMT/BST Conversion Table
Full 24-hour table. In winter UK time and UTC are the same; in summer the UK is one hour ahead.
| UTC (24h) | UTC (12h) | GMT (UTC+0) | BST (UTC+1) |
|---|---|---|---|
| 00:00 | 12:00 AM | 12:00 AM | 1:00 AM |
| 01:00 | 1:00 AM | 1:00 AM | 2:00 AM |
| 02:00 | 2:00 AM | 2:00 AM | 3:00 AM |
| 03:00 | 3:00 AM | 3:00 AM | 4:00 AM |
| 04:00 | 4:00 AM | 4:00 AM | 5:00 AM |
| 05:00 | 5:00 AM | 5:00 AM | 6:00 AM |
| 06:00 | 6:00 AM | 6:00 AM | 7:00 AM |
| 07:00 | 7:00 AM | 7:00 AM | 8:00 AM |
| 08:00 | 8:00 AM | 8:00 AM | 9:00 AM |
| 09:00 | 9:00 AM | 9:00 AM | 10:00 AM |
| 10:00 | 10:00 AM | 10:00 AM | 11:00 AM |
| 11:00 | 11:00 AM | 11:00 AM | 12:00 PM |
| 12:00 | 12:00 PM | 12:00 PM | 1:00 PM |
| 13:00 | 1:00 PM | 1:00 PM | 2:00 PM |
| 14:00 | 2:00 PM | 2:00 PM | 3:00 PM |
| 15:00 | 3:00 PM | 3:00 PM | 4:00 PM |
| 16:00 | 4:00 PM | 4:00 PM | 5:00 PM |
| 17:00 | 5:00 PM | 5:00 PM | 6:00 PM |
| 18:00 | 6:00 PM | 6:00 PM | 7:00 PM |
| 19:00 | 7:00 PM | 7:00 PM | 8:00 PM |
| 20:00 | 8:00 PM | 8:00 PM | 9:00 PM |
| 21:00 | 9:00 PM | 9:00 PM | 10:00 PM |
| 22:00 | 10:00 PM | 10:00 PM | 11:00 PM |
| 23:00 | 11:00 PM | 11:00 PM | 12:00 AMnext day |
* On BST, 23:00 UTC is already 12:00 AM on the next calendar day in the UK.
A UK Workday in UTC
The UK workday sits on the same UTC date all year, but it shifts by an hour with the season, which is why a fixed UTC schedule drifts against UK office hours:
| In the UK | On GMT (UTC+0) | On BST (UTC+1) |
|---|---|---|
| Starts, 9:00 AM | 09:00 UTC | 08:00 UTC |
| Ends, 5:00 PM | 17:00 UTC | 16:00 UTC |
The Two Changes and What UTC Does
UK clocks go forward at 1:00 AM GMT on the last Sunday in March (to 2:00 AM BST) and back at 2:00 AM BST on the last Sunday in October (to 1:00 AM GMT). UTC never moves, so only the UK offset changes: 14:00 UTC is 2:00 PM in London before the change and 3:00 PM after it.
UTC and GMT show the same clock time, but they are not the same thing. UTC is kept by atomic clocks and has no seasons; GMT is the UK's winter time zone. That is why a log or an invite marked “GMT” in July is an hour out from London's wall clock, and why this page keeps both columns.
Converting a Timestamp in Code
A UTC timestamp ends in Z. The same moment written for BST carries the offset instead: 2026-07-01T15:00:00Z and 2026-07-01T16:00:00+01:00 are one instant, and the local date is the same. Libraries convert it for you if you give them the zone name Europe/London instead of a fixed number.
# Python 3.9+
from datetime import datetime
from zoneinfo import ZoneInfo
datetime.fromisoformat("2026-07-01T15:00:00+00:00").astimezone(ZoneInfo("Europe/London"))// JavaScript
new Date("2026-07-01T15:00:00Z").toLocaleString("en-US", { timeZone: "Europe/London" })Both give the BST time shown above.