Time zone bugs all come from one confusion: an instant is universal, but its wall-clock name differs by zone — and the naming rules (including daylight saving) change twice a year on politically chosen dates. This converter runs on the browser's own IANA database, the same rules your OS clock trusts.
The DST trap, illustrated
New York and London are "5 hours apart" — except for about three weeks a year when the US has switched to summer time and the UK hasn't (or vice versa), making it 4. Any converter using fixed offsets misbooks meetings in those windows; zone-database conversion doesn't, because it evaluates the rules for the specific date you pick.
Offsets are politics, not physics
India runs UTC+5:30, Nepal +5:45, Newfoundland −3:30. China spans five geographic zones on one clock; Spain lives on Berlin time for World-War-II-era reasons. The half-hour zones are why this converter shows minute-precision differences instead of assuming whole hours.
Finding meeting windows
The overlap badge intersects 9:00–18:00 working days in both zones: London–New York share 4 hours; Sydney–London share none, which is why one side always suffers. For the humane option with three-plus zones, rotate who takes the bad slot.
Related time tools
Once times align, duration math is the time duration calculator's job. Programmers who'd rather ship one universal integer across zones — that's the entire philosophy of the Unix timestamp converter, and the military time converter removes AM/PM ambiguity within a single zone.
IANA zone data ships in your browser — works offline, updates with browser updates.