BST to IST Time Converter
IST is 4 hours and 30 minutes ahead of BST. BST is UTC+1:00, and IST is UTC+5:30.
Best Time to Call Between BST and IST
Both zones are inside normal business hours between 9:00 AM and 1:00 PM BST — that's 1:30 PM to 5:30 PM IST. That's a 4-hour window.
both at work BST only IST only neither — hours along the strip are BST.
Common Times Converted
BST on the left, IST on the right.
BST to IST: Full 24-Hour Conversion Table
Shaded rows are working hours; the darker shade marks the hours when both zones are at work.
| BST | IST | Working hours |
|---|---|---|
| 12:00 AM | 4:30 AM | — |
| 1:00 AM | 5:30 AM | — |
| 2:00 AM | 6:30 AM | — |
| 3:00 AM | 7:30 AM | — |
| 4:00 AM | 8:30 AM | — |
| 5:00 AM | 9:30 AM | IST only |
| 6:00 AM | 10:30 AM | IST only |
| 7:00 AM | 11:30 AM | IST only |
| 8:00 AM | 12:30 PM | IST only |
| 9:00 AM | 1:30 PM | Both zones |
| 10:00 AM | 2:30 PM | Both zones |
| 11:00 AM | 3:30 PM | Both zones |
| 12:00 PM | 4:30 PM | Both zones |
| 1:00 PM | 5:30 PM | BST only |
| 2:00 PM | 6:30 PM | BST only |
| 3:00 PM | 7:30 PM | BST only |
| 4:00 PM | 8:30 PM | BST only |
| 5:00 PM | 9:30 PM | — |
| 6:00 PM | 10:30 PM | — |
| 7:00 PM | 11:30 PM | — |
| 8:00 PM | 12:30 AM next day | — |
| 9:00 PM | 1:30 AM next day | — |
| 10:00 PM | 2:30 AM next day | — |
| 11:00 PM | 3:30 AM next day | — |
What BST and IST Actually Are
BST — British Summer Time
London, Manchester, Birmingham, Glasgow, and the rest of the UK from late March to late October. Standing at UTC+1:00 as written, and the region does change its clocks, so its live offset moves by an hour twice a year. The next change is on Sunday, October 25, 2026, to GMT. BST also stands for Bangladesh Standard Time (UTC+6). BDT is the clearer label for that one.
British Summer Time began in 1916 as a wartime fuel-saving measure and has run every year since, making it one of the oldest continuous daylight saving schemes in the world.
IST — India Standard Time
Mumbai, Delhi, Bengaluru, Chennai, Kolkata, Hyderabad — and Colombo. Standing at UTC+5:30 as written, and the region does not change its clocks, so that offset holds all year. IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.
India runs a single time zone across a country wide enough for two, which is why sunrise in the north-east can come nearly two hours before Mumbai's. Proposals for a second zone resurface regularly and have never been adopted.
What This Means in Practice
Expect times on the half hour
IST sits on a 30-minute offset rather than a whole hour, so a round number on one side is never a round number on the other. A 9:00 meeting becomes 30 minutes past the hour, which is exactly the detail calendar invitations get wrong when someone converts in their head.
This gap is not fixed
BST changes its clocks and IST does not, so the difference between them moves by an hour twice a year. A recurring meeting set now will drift for one side from Sunday, October 25, 2026 unless someone resets it.
Major Cities in Each Zone
Cities on BST
Cities on IST
Frequently Asked Questions
What is the time difference between BST and IST?
IST is 4 hours and 30 minutes ahead of BST.
What is 9:00 AM BST in IST?
9:00 AM BST is 1:30 PM IST.
What are the best hours to schedule a call between BST and IST?
Between 9:00 AM and 1:00 PM BST, which is 1:30 PM to 5:30 PM IST. Both sides are inside normal business hours through that window.
Does the difference between BST and IST change during the year?
Yes. BST observes daylight saving and IST does not, so the gap shifts by an hour at least twice a year. The next clock change is on Sunday, October 25, 2026.
Does BST always mean British Summer Time?
BST also stands for Bangladesh Standard Time (UTC+6). BDT is the clearer label for that one.
Does IST always mean India Standard Time?
IST also stands for Irish Standard Time (UTC+1) and Israel Standard Time (UTC+2). This page covers the Indian one, which is by far the most searched.