Tokyo is 12 hours ahead of São Paulo. Put the other way round: São Paulo is 12 hours behind Tokyo.
São Paulo is UTC-3 in summer and UTC-3 in winter; Tokyo is UTC+9 and UTC+9.
A nine-to-five in São Paulo and a nine-to-five in Tokyo 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.
Neither São Paulo nor Tokyo changes its clocks, so this gap is the same every day of the year.
| São Paulo | Tokyo |
|---|---|
| 08:00 | 20:00 |
| 09:00 | 21:00 |
| 10:00 | 22:00 |
| 11:00 | 23:00 |
| 12:00 | 00:00 next day |
| 13:00 | 01:00 next day |
| 14:00 | 02:00 next day |
| 15:00 | 03:00 next day |
| 16:00 | 04:00 next day |
| 17:00 | 05:00 next day |
| 18:00 | 06:00 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.