Hong Kong is 11 hours ahead of Buenos Aires. Put the other way round: Buenos Aires is 11 hours behind Hong Kong.
Buenos Aires is UTC-3 in summer and UTC-3 in winter; Hong Kong is UTC+8 and UTC+8.
A nine-to-five in Buenos Aires and a nine-to-five in Hong Kong 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 Buenos Aires nor Hong Kong changes its clocks, so this gap is the same every day of the year.
| Buenos Aires | Hong Kong |
|---|---|
| 08:00 | 19:00 |
| 09:00 | 20:00 |
| 10:00 | 21:00 |
| 11:00 | 22:00 |
| 12:00 | 23:00 |
| 13:00 | 00:00 next day |
| 14:00 | 01:00 next day |
| 15:00 | 02:00 next day |
| 16:00 | 03:00 next day |
| 17:00 | 04:00 next day |
| 18:00 | 05:00 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.