There is no time difference between Mumbai and Kolkata. Both cities use Indian Standard Time (IST, UTC+5:30). When it's 12:00 PM in Mumbai, it's also 12:00 PM in Kolkata.
India uses a single timezone across the country and does not observe daylight saving time, so all Indian cities remain synchronized.
Any time works! Since both cities share the same timezone, you can schedule calls during standard business hours (9:00 AM - 6:00 PM) without any time conversion needed.
Mumbai and Kolkata are India's two major port cities. Mumbai is on the west coast, while Kolkata is in the east. Direct flights connect the cities in about 2.5 hours.