Convert IST to BST
BST = IST −4 h 30 min
BST is 4 hours 30 minutes behind IST. IST is always UTC+5:30 and BST is always UTC+1, so this gap is the same on every date.
IST · India Standard Time · UTC+5:30
6:45PM
Tuesday, November 3, 2026
BST · British Summer Time · UTC+1
2:15PM
Tuesday, November 3, 2026
The UK is on GMT (UTC+0) right now.
- Next clock change: March 28, 2027. The UK moves to BST (UTC+1), so the UK is then 4 hours 30 minutes behind India.
- Next clock change: October 31, 2027. The UK moves to GMT (UTC+0), so the UK is then 5 hours 30 minutes behind India.
IST to BST for every hour
Each BST column holds for part of the year (dates in the header for 2027). The first uses the fixed offsets (IST UTC+5:30, BST UTC+1); the others give local clock time when daylight saving time changes the gap. Until 4:30 AM IST, BST is still on the previous calendar day.
| IST | BST −4 h 30 minfixed offsets | BST −5 h 30 minJan 1 – Mar 28, Oct 31 – Dec 31 | 24-hour |
|---|---|---|---|
| 12:00 AM | 7:30 PM −1 day | 6:30 PM −1 day | 00:00 → 19:30 |
| 1:00 AM | 8:30 PM −1 day | 7:30 PM −1 day | 01:00 → 20:30 |
| 2:00 AM | 9:30 PM −1 day | 8:30 PM −1 day | 02:00 → 21:30 |
| 3:00 AM | 10:30 PM −1 day | 9:30 PM −1 day | 03:00 → 22:30 |
| 4:00 AM | 11:30 PM −1 day | 10:30 PM −1 day | 04:00 → 23:30 |
| 5:00 AM | 12:30 AM | 11:30 PM −1 day | 05:00 → 00:30 |
| 6:00 AM | 1:30 AM | 12:30 AM | 06:00 → 01:30 |
| 7:00 AM | 2:30 AM | 1:30 AM | 07:00 → 02:30 |
| 8:00 AM | 3:30 AM | 2:30 AM | 08:00 → 03:30 |
| 9:00 AM | 4:30 AM | 3:30 AM | 09:00 → 04:30 |
| 10:00 AM | 5:30 AM | 4:30 AM | 10:00 → 05:30 |
| 11:00 AM | 6:30 AM | 5:30 AM | 11:00 → 06:30 |
| 12:00 PM | 7:30 AM | 6:30 AM | 12:00 → 07:30 |
| 1:00 PM | 8:30 AM | 7:30 AM | 13:00 → 08:30 |
| 2:00 PM | 9:30 AM | 8:30 AM | 14:00 → 09:30 |
| 3:00 PM | 10:30 AM | 9:30 AM | 15:00 → 10:30 |
| 4:00 PM | 11:30 AM | 10:30 AM | 16:00 → 11:30 |
| 5:00 PM | 12:30 PM | 11:30 AM | 17:00 → 12:30 |
| 6:00 PM | 1:30 PM | 12:30 PM | 18:00 → 13:30 |
| 7:00 PM | 2:30 PM | 1:30 PM | 19:00 → 14:30 |
| 8:00 PM | 3:30 PM | 2:30 PM | 20:00 → 15:30 |
| 9:00 PM | 4:30 PM | 3:30 PM | 21:00 → 16:30 |
| 10:00 PM | 5:30 PM | 4:30 PM | 22:00 → 17:30 |
| 11:00 PM | 6:30 PM | 5:30 PM | 23:00 → 18:30 |
Bold rows fall inside office hours (9:00 to 17:00) on both sides. The dot marks the current IST hour.
The IST times people look up most
| IST | BST −4 h 30 min | BST −5 h 30 min |
|---|---|---|
| 6:00 PM | 1:30 PM | 12:30 PM |
| 11:00 PM | 6:30 PM | 5:30 PM |
| 9:02 AM | 4:32 AM | 3:32 AM |
| 9:02 PM | 4:32 PM | 3:32 PM |
| 9:30 AM | 5:00 AM | 4:00 AM |
| 9:30 PM | 5:00 PM | 4:00 PM |
| 6:52 PM | 2:22 PM | 1:22 PM |
| 11:20 AM | 6:50 AM | 5:50 AM |
Does the difference change during the year?
As written, no: IST is always UTC+5:30 and BST is always UTC+1, so the gap is 4 hours 30 minutes on every date. But the UK uses BST only in summer, and people often keep writing “BST” when they mean the local time. Between the local clocks of India and the UK, the gap is 5 hours 30 minutes or 4 hours 30 minutes:
| From | What changes | India | The UK | BST vs IST |
|---|---|---|---|---|
| January 1 | Start of the year | IST (UTC+5:30) | GMT (UTC+0) | −5 h 30 min |
| March 29 | The UK moves to BST (UTC+1) | IST (UTC+5:30) | BST (UTC+1) | −4 h 30 min |
| October 25 | The UK moves to GMT (UTC+0) | IST (UTC+5:30) | GMT (UTC+0) | −5 h 30 min |
| From | What changes | India | The UK | BST vs IST |
|---|---|---|---|---|
| January 1 | Start of the year | IST (UTC+5:30) | GMT (UTC+0) | −5 h 30 min |
| March 28 | The UK moves to BST (UTC+1) | IST (UTC+5:30) | BST (UTC+1) | −4 h 30 min |
| October 31 | The UK moves to GMT (UTC+0) | IST (UTC+5:30) | GMT (UTC+0) | −5 h 30 min |
Converting IST to BST by hand
With the fixed offsets, take away 4 hours 30 minutes: 3:30 PM IST is 11:00 AM BST.
With the −5 h 30 min gap (Jan 1 – Mar 28, Oct 31 – Dec 31), take away 5 hours 30 minutes: 3:30 PM IST is 10:00 AM BST.
Going back from BST to IST, do the opposite: the BST to IST page has its own table.
Where the IST and BST working days overlap
IST to BST (−4 h 30 min): Two 9:00–17:00 days share 3 hours 30 minutes: 1:30 PM to 5:00 PM IST, which is 9:00 AM to 12:30 PM BST.
−5 h 30 min (from Jan 1 to Mar 28 and Oct 31 to Dec 31, 2027): Two 9:00–17:00 days share 2 hours 30 minutes: 2:30 PM to 5:00 PM IST, which is 9:00 AM to 11:30 AM BST.
A meeting fixed in one city’s calendar moves by an hour for the other when the gap changes. Calendar apps handle this when the event is saved in a named zone (for example Asia/Kolkata) rather than as a fixed offset.
What IST and BST mean
India Standard Time
IST here is India Standard Time, UTC+5:30, used in all of India all year: no daylight saving time and a single zone for the whole country.
IST can also mean Israel Standard Time (UTC+2, Israel) or Irish Standard Time (UTC+1, Ireland, in summer). This page uses India Standard Time, the meaning people searching for this conversion have in mind. For another one, type the city into the time zone converter.
British Summer Time
BST is UTC+1, the UK’s summer time, from 1:00 AM GMT on the last Sunday of March to 1:00 AM GMT on the last Sunday of October (Summer Time Act 1972 as amended in 2002). In winter the UK is on GMT, UTC+0.