When are you both actually free?
The gap between two cities is not one number. It moves through the year, and the hours you share move with it. These pages work out both, for a whole year at a time.
Why a converter does not answer this
A time zone converter tells you what the clock says somewhere else right now. That is a different question from the one people in two cities actually have, which is when both of them are awake, free, and able to do something together.
It is also not a fixed answer. Countries change their clocks on different dates, and in opposite directions either side of the equator, so the gap between two cities can take several different values in one year. Every page here lists all of them, with the exact dates they change.
Pairs
| Cities | Shared | Gap changes | Evening |
|---|---|---|---|
| London and Sydney Never share an evening, and the morning window moves by two hours in April. | 8h/day | 4× a year | never |
“Shared” counts hours when both cities are between 07:00 and 23:00, using the period in force today. Figures come from the same time zone database your operating system uses.