Best overlap: 8:00 AM to 4:00 PM in Istanbul is 10:30 AM to 6:30 PM in Kolkata.
Target 8:00 AM to 4:00 PM in Istanbul, which lands at 10:30 AM to 6:30 PM for the Kolkata side. Kolkata is 2.5 hours ahead of Istanbul, but with 8 hours of common ground you can hold morning or afternoon meetings without anyone working odd hours.
| Local time | 12am | 1am | 2am | 3am | 4am | 5am | 6am | 7am | 8am | 9am | 10am | 11am | 12pm | 1pm | 2pm | 3pm | 4pm | 5pm | 6pm | 7pm | 8pm | 9pm | 10pm | 11pm |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Istanbul Europe/Istanbul | ||||||||||||||||||||||||
Kolkata Asia/Kolkata |
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. -