Moscow is 1 hour ahead of Warsaw

Best overlap: 8:00 AM to 5:00 PM in Warsaw is 9:00 AM to 6:00 PM in Moscow.

For a call that suits both sides, look at 8:00 AM to 5:00 PM in Warsaw / 9:00 AM to 6:00 PM in Moscow. Moscow is 1 hour ahead of Warsaw, but you still share a generous 9 hours of overlap, so scheduling is easy and there's room to move a meeting when you need to. Remember that Warsaw shifts for daylight saving and Moscow doesn't, so recalculate the overlap after each clock change.