Why store a zone name rather than an offset?

An offset is a consequence of the zone and the date. It changes twice a year, and governments occasionally change the rules — a name survives that, an offset does not.

Timezone Offset Helper

Compare one instant across several IANA time zones.

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About this tool

Shows one instant as it reads in several time zones at once, using the browser's own zone database. Offsets change with daylight saving, which is why zones are identified by name rather than by a fixed offset.

Limitations

Zone data comes from your browser's Intl implementation, so availability depends on the platform.

Questions

Why store a zone name rather than an offset?: An offset is a consequence of the zone and the date. It changes twice a year, and governments occasionally change the rules — a name survives that, an offset does not.

Privacy

This page does its work in your browser. What you paste is processed by JavaScript running on your own device and is never sent to a DevToolery server — there is no server that could receive it. The page itself is a static file delivered by a CDN. See exactly what is stored.