Kolkata to LondonTime Converter

Kolkata to London: the time difference

On 2026-10-05 at 9:00 AM in Kolkata, it is 4:30 AM in London (Monday, October 5, 2026). London is 4 hours and 30 minutes behind of Kolkata.

Asia/Kolkata is the IANA identifier used for India Standard Time. Older systems may use the Asia/Calcutta alias; both refer to the same modern time rules. London is often described as being on GMT, but it uses British Summer Time during part of the year. Choosing Europe/London keeps both seasons attached to the same calendar event.

24-hour conversion table

Source date: 2026-10-05 in Kolkata. Each row is a real instant; the destination date is shown explicitly. Repeated hours appear twice and nonexistent hours are labeled.

Does the time difference change during 2026?

Yes. The daily reference calculation finds 4.5 and 5.5-hour differences across the year. A repeating meeting tied to one city's clock can move on the other city's calendar.

Ranges sample each date at 12:00 UTC. A transition can occur partway through the first or last date. Use the converter for the precise instant. Calculated from this build’s Intl time-zone rules; future legislation may change them.

Kolkata: No UTC offset change is found in the 2026 reference data. The offset is UTC+05:30.

London: The 2026 reference data includes UTC+00:00 and UTC+01:00. Select the actual meeting date: one fixed offset will not describe the whole year.

Best time to call London from Kolkata

For a one-hour call on 2026-10-05, these example start times fit a 9 AM–6 PM workday in both cities. A shared workday is not a guarantee that a person is free.

Customize working hours for Kolkata and London.

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