Kolkata zone
GMT+5:30 (GMT+5:30)
London zone
GMT+1 (GMT+1)
Difference
4h 30m behind Kolkata
Business overlap
3h (9-5 windows)
Working hours overlap
Each cell is one hour in Kolkata. Filled cells mark when 9 AM – 5 PM in Kolkata and London both apply.
3 hours per day
- Kolkata
- GMT+5:30
- London
- GMT+1
- Difference
- -4h 30m
- Business overlap
- 3h
Hour-by-hour conversion
Each row shows the matching local time in London for an hour in Kolkata.
| Kolkata | London | Day | Window |
|---|---|---|---|
| 12:00 AM | 7:30 PM | previous day | — |
| 1:00 AM | 8:30 PM | previous day | — |
| 2:00 AM | 9:30 PM | previous day | — |
| 3:00 AM | 10:30 PM | previous day | — |
| 4:00 AM | 11:30 PM | previous day | — |
| 5:00 AM | 12:30 AM | same day | — |
| 6:00 AM | 1:30 AM | same day | — |
| 7:00 AM | 2:30 AM | same day | — |
| 8:00 AM | 3:30 AM | same day | — |
| 9:00 AM | 4:30 AM | same day | — |
| 10:00 AM | 5:30 AM | same day | — |
| 11:00 AM | 6:30 AM | same day | — |
| 12:00 PM | 7:30 AM | same day | — |
| 1:00 PM | 8:30 AM | same day | — |
| 2:00 PM | 9:30 AM | same day | Both 9-5 |
| 3:00 PM | 10:30 AM | same day | Both 9-5 |
| 4:00 PM | 11:30 AM | same day | Both 9-5 |
| 5:00 PM | 12:30 PM | same day | — |
| 6:00 PM | 1:30 PM | same day | — |
| 7:00 PM | 2:30 PM | same day | — |
| 8:00 PM | 3:30 PM | same day | — |
| 9:00 PM | 4:30 PM | same day | — |
| 10:00 PM | 5:30 PM | same day | — |
| 11:00 PM | 6:30 PM | same day | — |
Best meeting windows
If both teams keep standard 9 AM – 5 PM hours, the overlap window is roughly 2:00 PM – 5:00 PM in Kolkata time. That gives you 3 hours per workday for live meetings.
Tighter overlap is achievable by having the side with later working hours start earlier, or by treating the first and last hours of each side as flexible. The bar above marks every hour where both cities sit inside a 9 AM – 5 PM window.
About converting Kolkata time to London time
Kolkata follows the Asia/Kolkata time zone (currently GMT+5:30, GMT+5:30), while London follows Europe/London (currently GMT+1, GMT+1). London is 4h 30m behind Kolkata right now.
London observes daylight saving time, while Kolkata does not. The offset between the two cities changes by one hour at the daylight saving transitions.
Daylight saving transitions in 2026
Kolkata
Does not observe daylight saving time.
London
- Spring forward · Sunday, March 29, 2026
- Fall back · Sunday, October 25, 2026
Reverse this conversion
London to Kolkata
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Frequently asked questions
- How many hours is Kolkata from London?
- London is 4h 30m behind Kolkata right now.
- What time is 9:00 AM Kolkata in London?
- 9:00 AM in Kolkata is 4:30 AM in London.
- What time is 5:00 PM Kolkata in London?
- 5:00 PM in Kolkata is 12:30 PM in London.
- When do Kolkata and London business hours overlap?
- Standard 9 AM - 5 PM working hours overlap for about 3 hours, roughly from 2:00 PM to 5:00 PM in Kolkata time.
- Does daylight saving time change the difference between Kolkata and London?
- London observes daylight saving time while Kolkata does not, so the offset between them changes by one hour twice a year.
Local time page
Time in Kolkata
Local time page
Time in London