Best overlap: 8:15 AM to 6:15 PM in Kathmandu is 8:00 AM to 6:00 PM in Kolkata.
Your shared working hours run 8:15 AM to 6:15 PM in Kathmandu (8:00 AM to 6:00 PM in Kolkata). Kolkata is 0.25 hours behind Kathmandu, and with 10 hours of overlap you can even run back-to-back calls without stepping outside business hours.
A complete guide to time zones in 2025, from UTC and GMT differences to Daylight Saving Time changes, IANA database rules, abbreviation pitfalls, and developer best practices for handling global time. -