Time Zone Converter

See a time across major world time zones. Free, runs entirely in your browser — no signup, and nothing you paste in is uploaded.

Offsets are not fixed properties of places. A timezone is a set of rules that changes with legislation, and governments alter them with weeks of notice, which is why timezone data ships as a database that needs updating rather than as a lookup table. Storing a future appointment as UTC alone can therefore make it wrong later.

Daylight saving is where scheduling across zones goes wrong, because not everywhere observes it and those that do switch on different dates. There is a window each spring and autumn where the usual gap between two cities is an hour off, and a recurring meeting silently moves for one side of the call.