Delhi is 3 hours 30 minutes ahead of Madrid. Put the other way round: Madrid is 3 hours 30 minutes behind Delhi.
Madrid is UTC+2 in summer and UTC+1 in winter; Delhi is UTC+5:30 and UTC+5:30.
Working 09:00 to 17:00 in both cities leaves 4.5 hours in common: 09:00 to 13:30 in Madrid, which is 12:30 to 17:00 in Delhi. Those are the hours to aim a call at.
Madrid changes its clocks for summer and Delhi does not, so there is no single answer: the gap is 3 hours 30 minutes for the northern summer and 4 hours 30 minutes for the rest of the year.
| Madrid | Delhi |
|---|---|
| 08:00 | 11:30 |
| 09:00 | 12:30 |
| 10:00 | 13:30 |
| 11:00 | 14:30 |
| 12:00 | 15:30 |
| 13:00 | 16:30 |
| 14:00 | 17:30 |
| 15:00 | 18:30 |
| 16:00 | 19:30 |
| 17:00 | 20:30 |
| 18:00 | 21:30 |
This page covers one pair. TimeGap takes a list: add every city you care about, drag one marker, and every row reads the same instant on its own clock. It marks the hours you would actually take a call, finds the window where the most people are reachable, flags public holidays, and puts the time you pick straight into Outlook or Google Calendar.