Best overlap: 1:00 PM to 6:00 PM in Perth is 8:00 AM to 1:00 PM in Helsinki.
The hours that work for both Perth and Helsinki are 1:00 PM to 6:00 PM (Perth) and 8:00 AM to 1:00 PM (Helsinki). The overlap sits at about 5 hours; aim for the heart of it so the call isn't too early for one team or too late for the other. A quick caveat — Helsinki's clocks move for daylight saving and Perth's don't, so the times here are right for only part of the year.
| 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 | ||||||||||||||||||||||||
Helsinki Europe/Helsinki |
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. -