BST to IST time converter
Enter a time in BST to get the matching time in IST, whether it falls on the next or previous day, and a full 24-hour table. Handy for planning calls between London in summer and Mumbai and New Delhi.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter time in bst and day in bst (optional).
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
IST time = BST time + 4.5 hours, because IST is UTC+5:30 and BST is UTC+1. If the result reaches 24:00 or more, subtract 24 hours and move to the next day; if it drops below 00:00, add 24 hours and move to the previous day.
Example
Inputs: Time in BST = 22:00, Day in BST (optional) = Thursday. Result: Time in IST: 02:30; Day change: Next day (+1); Offset difference (IST minus BST): 4.5 hours.
Limits and caveats
- Fixed offsets are used: BST = UTC+1 and IST = UTC+5:30, whatever the date.
- BST is used only from the last Sunday of March to the last Sunday of October; London uses GMT (UTC+0) the rest of the year; the tool does not apply that change.
- BST here is British Summer Time (UTC+1), not Bangladesh Standard Time (UTC+6).
Questions about this tool
What time is 09:00 BST in IST?
09:00 BST is 13:30 IST on the same day, because IST is 4.5 hours ahead of BST.
Does daylight saving time change the result?
The tool keeps BST at UTC+1 all year. BST is used only from the last Sunday of March to the last Sunday of October; London uses GMT (UTC+0) the rest of the year; in winter the gap between London and IST is 5.5 hours.
Which IST does this tool use?
Here IST means India Standard Time, UTC+5:30. The same letters are used for Irish Standard Time (UTC+1, Irish summer time) and Israel Standard Time (UTC+2).