Best overlap: 8:30 AM to 12:30 PM in Reykjavik is 2:00 PM to 6:00 PM in Kolkata.
Keep meetings inside 8:30 AM to 12:30 PM in Reykjavik — that maps to 2:00 PM to 6:00 PM in Kolkata. You share roughly 4 hours a day. That's enough for regular meetings, but treat the window as prime time and guard it.
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. -