Best overlap: 11:00 AM to 6:00 PM in Perth is 8:30 AM to 3:30 PM in Kolkata.
The overlap falls at 11:00 AM to 6:00 PM in Perth, or 8:30 AM to 3:30 PM if you're in Kolkata. With 7 hours in common, treat scheduling almost as if the two cities were in the same region.
| 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Perth Australia/Perth | ||||||||||||||||||||||||
Kolkata Asia/Kolkata |
The US to Australia gap runs 14 to 19 hours depending on the month, and someone is always in tomorrow. Exact overlap windows for every US coast, the double-DST trap, and a rotation rule that keeps it fair. -
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. -