Meeting Time Finder Across Timezones

Plots every participant's working hours on the same 24-hour UTC row and highlights the hours where everyone is online. Each row also shows the local hour in that zone so you can read the slot in any local calendar. Built from Intl.DateTimeFormat so DST transitions are handled correctly for the chosen date — pick a date that falls inside the meeting week and the offsets respect summer/winter time shifts. No accounts, no calendar access, no API calls.

Picking the date matters more than it looks, because an offset is a property of a moment rather than of a place. The gap between London and New York is five hours for most of the year and four for the two weeks in March when the clocks have moved in one country and not yet in the other, and the southern hemisphere shifts the other way entirely: Sydney and London swing between nine and eleven hours apart across the year. A slot agreed in one season quietly moves in the next.

A clean overlap is not always available, and the honest answer is then which participants lose. Once a group spans more than about eight hours of longitude there is no hour inside everyone's working day, and someone takes an early morning or a late evening. Rotating who takes it is the usual fix; picking the hour that happens to suit the organiser is the usual failure.

The working hours here are a rectangle, and real availability is not. Lunch, school runs, prayer times, a four-day week and a Friday-Saturday weekend are all invisible to this, so a slot the grid calls green can still be one nobody in that row would accept.

Every row is computed from your browser's copy of the time zone database. A recent change to a country's rules only appears once that browser has been updated, which is worth knowing when scheduling far ahead into a zone whose government has just legislated a shift.