Mumbai is 12 hours 30 minutes ahead of San Francisco. Put the other way round: San Francisco is 12 hours 30 minutes behind Mumbai.
San Francisco is UTC-7 in summer and UTC-8 in winter; Mumbai is UTC+5:30 and UTC+5:30.
A nine-to-five in San Francisco and a nine-to-five in Mumbai do not overlap at all. Somebody has to move: the nearest workable slots are early morning in one city or late evening in the other, which is the kind of thing the planner is for.
San Francisco changes its clocks for summer and Mumbai does not, so there is no single answer: the gap is 12 hours 30 minutes for the northern summer and 13 hours 30 minutes for the rest of the year.
| San Francisco | Mumbai |
|---|---|
| 08:00 | 20:30 |
| 09:00 | 21:30 |
| 10:00 | 22:30 |
| 11:00 | 23:30 |
| 12:00 | 00:30 next day |
| 13:00 | 01:30 next day |
| 14:00 | 02:30 next day |
| 15:00 | 03:30 next day |
| 16:00 | 04:30 next day |
| 17:00 | 05:30 next day |
| 18:00 | 06:30 next day |
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.