The practical UTC guide
UTC to local time, without the guesswork.
Start with an instant, then choose where you want to read it.
What does Z mean?
In 2026-10-06T14:30:00Z, the Z marks UTC. The same instant is 22:30 in Shanghai and 10:30 in New York on that date. Keep the date: offsets depend on the season.
A city is more useful than a fixed offset.
New York uses UTC−05:00 in winter and UTC−04:00 during daylight saving time. A regional identifier such as America/New_York lets the system apply the rule for the date being converted. A bare offset such as −05:00 does not describe future or past seasonal changes.
Unix seconds and milliseconds
Unix timestamps count time from 1970-01-01 00:00:00 UTC. 1722177000 seconds and 1722177000000 milliseconds represent the same instant. Choose the matching unit in the demo. The current App Store release accepts seconds; explicit milliseconds support is in the next update.
Dates without an offset
The converter treats 2026-10-06 14:30:00 as UTC. If your source means a local wall-clock time, include its known numeric offset. During a daylight-saving fall-back, the same local clock time may occur twice; the offset distinguishes the instants.
What about leap seconds?
The new parser rejects seconds equal to 60 instead of silently normalizing them. If your source includes leap seconds, normalize it with a tool that explicitly supports that time scale before using this converter.
Try a real example
For a wrong result, send a reproducible report including the input, destination time zone and macOS version. Time-zone rules are supplied by the operating system and can change.