BST vs IST time zone comparison

How BST and IST compare

British Summer Time (BST) sits at UTC+01:00 today, while India Standard Time (IST) is at UTC+05:30. The current gap is 4 hours, with BST behind IST. In practical terms, if your morning starts at 9 AM in London, your counterpart in Delhi is seeing 13:30 on their own watch at that exact moment.

BST is the working clock for London, Birmingham and Manchester. BST also refers to Bangladesh Standard Time (Asia/Dhaka). UK usage dominates search volume. IST covers Delhi, Mumbai and Kolkata. IST is ambiguous: India Standard Time, Irish Standard Time, and Israel Standard Time all share the abbreviation. We default to India (largest population). For Ireland use Dublin or WET, for Israel use Asia/Jerusalem. If your team is split between these two regions, the table above is the quickest way to spot the daily overlap window without doing the offset arithmetic in your head.

Daylight saving matters here. British Summer Time shifts forward an hour on the second Sunday of March (US) or the last Sunday of March (Europe) and back on the first Sunday of November or last Sunday of October. India Standard Time stays on a fixed offset year-round. The IANA tzdata baked into this page handles every transition automatically, so the table reflects the correct wall-clock times for today's date. For dates further out, use the converter linked above and pick the target date explicitly.

Common scheduling traps are easy to avoid here. Pick a wall-clock time on one side, read the matching wall-clock on the other from the table, and write both into the calendar invite, never just the difference. If the meeting falls in the week of a DST changeover and one of these zones shifts, the absolute clock will drift by an hour from what the recipient expects. The table is computed for today's date, so for a future meeting open the converter linked above and pick the exact date.

One last note for asynchronous teams: business-hour overlap is the wrong metric for handoff workflows. If you operate on a follow-the-sun model, you actually want zero overlap, with one team logging off as the other starts. BST and IST differ by 4 hours, which gives you partial coverage. Add a zone in between if you want full 24-hour rotation.