Mumbai is 2 hours 30 minutes behind Hong Kong. Put the other way round: Hong Kong is 2 hours 30 minutes ahead of Mumbai.
Hong Kong is UTC+8 in summer and UTC+8 in winter; Mumbai is UTC+5:30 and UTC+5:30.
Working 09:00 to 17:00 in both cities leaves 5.5 hours in common: 11:30 to 17:00 in Hong Kong, which is 09:00 to 14:30 in Mumbai. Those are the hours to aim a call at.
Neither Hong Kong nor Mumbai changes its clocks, so this gap is the same every day of the year.
| Hong Kong | Mumbai |
|---|---|
| 08:00 | 05:30 |
| 09:00 | 06:30 |
| 10:00 | 07:30 |
| 11:00 | 08:30 |
| 12:00 | 09:30 |
| 13:00 | 10:30 |
| 14:00 | 11:30 |
| 15:00 | 12:30 |
| 16:00 | 13:30 |
| 17:00 | 14:30 |
| 18:00 | 15:30 |
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.