Kolkata is 5.5 hours ahead of London. London uses GMT/BST while Kolkata uses India Standard Time (IST). India does not observe DST, so the difference varies between 4.5-5.5 hours depending on UK summer time.
When it's 12:00 PM in London, it's 5:30 PM in Kolkata.
Morning London works best! 9:00 AM in London is 2:30 PM in Kolkata - ideal for business calls.
Kolkata, formerly Calcutta, was the capital of British India until 1911. Today it remains a major economic and cultural hub. Direct flights between London and Kolkata take approximately 10-11 hours.