London zone
GMT+1 (GMT+1)
Kolkata zone
GMT+5:30 (GMT+5:30)
Difference
4h 30m ahead of London
Business overlap
4h (9-5 windows)
Working hours overlap
Each cell is one hour in London. Filled cells mark when 9 AM – 5 PM in London and Kolkata both apply.
4 hours per day
- London
- GMT+1
- Kolkata
- GMT+5:30
- Difference
- +4h 30m
- Business overlap
- 4h
Hour-by-hour conversion
Each row shows the matching local time in Kolkata for an hour in London.
| London | Kolkata | Day | Window |
|---|---|---|---|
| 12:00 AM | 4:30 AM | same day | — |
| 1:00 AM | 5:30 AM | same day | — |
| 2:00 AM | 6:30 AM | same day | — |
| 3:00 AM | 7:30 AM | same day | — |
| 4:00 AM | 8:30 AM | same day | — |
| 5:00 AM | 9:30 AM | same day | — |
| 6:00 AM | 10:30 AM | same day | — |
| 7:00 AM | 11:30 AM | same day | — |
| 8:00 AM | 12:30 PM | same day | — |
| 9:00 AM | 1:30 PM | same day | Both 9-5 |
| 10:00 AM | 2:30 PM | same day | Both 9-5 |
| 11:00 AM | 3:30 PM | same day | Both 9-5 |
| 12:00 PM | 4:30 PM | same day | Both 9-5 |
| 1:00 PM | 5:30 PM | same day | — |
| 2:00 PM | 6:30 PM | same day | — |
| 3:00 PM | 7:30 PM | same day | — |
| 4:00 PM | 8:30 PM | same day | — |
| 5:00 PM | 9:30 PM | same day | — |
| 6:00 PM | 10:30 PM | same day | — |
| 7:00 PM | 11:30 PM | same day | — |
| 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 | — |
Best meeting windows
If both teams keep standard 9 AM – 5 PM hours, the overlap window is roughly 9:00 AM – 1:00 PM in London time. That gives you 4 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 London time to Kolkata time
London follows the Europe/London time zone (currently GMT+1, GMT+1), while Kolkata follows Asia/Kolkata (currently GMT+5:30, GMT+5:30). Kolkata is 4h 30m ahead of London 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
London
- Spring forward · Sunday, March 29, 2026
- Fall back · Sunday, October 25, 2026
Kolkata
Does not observe daylight saving time.
Reverse this conversion
Kolkata to London
Open the converter
Plan a meeting between London and Kolkata
More conversions from London
Frequently asked questions
- How many hours is London from Kolkata?
- Kolkata is 4h 30m ahead of London right now.
- What time is 9:00 AM London in Kolkata?
- 9:00 AM in London is 1:30 PM in Kolkata.
- What time is 5:00 PM London in Kolkata?
- 5:00 PM in London is 9:30 PM in Kolkata.
- When do London and Kolkata business hours overlap?
- Standard 9 AM - 5 PM working hours overlap for about 4 hours, roughly from 9:00 AM to 1:00 PM in London time.
- Does daylight saving time change the difference between London and Kolkata?
- 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 London
Local time page
Time in Kolkata