Tehran is 1.5 hours ahead of Madrid

Best overlap: 8:00 AM to 5:00 PM in Madrid is 9:30 AM to 6:30 PM in Tehran.

Schedule calls for 8:00 AM to 5:00 PM in Madrid — your colleagues in Tehran will be online from 9:30 AM to 6:30 PM. Because you share 9 hours of the workday, there's no need to compromise; book the time that suits the meeting, not the map. These times hold for most of the year, but Madrid's daylight saving (which Tehran doesn't use) shifts them by an hour twice annually.