How time zone converter Works
The UTC arithmetic
Every zone is a UTC offset; conversion is subtraction and addition. Your time − your offset = UTC; UTC + their offset = their time. The calculator does this in both directions with the difference line highlighted — the single number that governs a working relationship across zones.
Working-hours marking
A time is not just a time — it lands in someone's day: working hours (8–18), early, evening, or asleep. The marker converts each converted time into a human cost. The skill of global scheduling is choosing slots where the marker reads "working" on both sides — and when impossible, rotating who pays.
The DST trap
Daylight saving switches are not synchronized: the US changes on different dates than Europe, and the southern hemisphere runs opposite. For 2–4 weeks each spring and fall, fixed offsets are wrong and recurring meetings silently move an hour for one side. The defense: schedule recurring meetings by UTC internally, or calendar-check the swap weeks twice a year.