Zurich is 1.5 hours behind Tehran
Best overlap: 9:30 AM to 6:30 PM in Tehran is 8:00 AM to 5:00 PM in Zurich.
Keep meetings inside 9:30 AM to 6:30 PM in Tehran — that maps to 8:00 AM to 5:00 PM in Zurich. Zurich is 1.5 hours behind Tehran, but the generous 9-hour window means both teams can meet well within their normal day. Finally, Zurich observes daylight saving and Tehran doesn't, so this window shifts by an hour for part of the year — recheck it each spring and autumn.