Time Zone Calculator
Uses your browser's built-in time zone database, so daylight saving time is accounted for automatically based on the date you enter — not just today's offset.
Free time zone calculator that converts a date and time from one time zone to another, using your browser's built-in time zone database — daylight saving time is handled automatically for the date you pick.
How it works
- Enter a date and time, and pick the "from" time zone
- Pick the "to" time zone
- See the converted time and the UTC offset difference
Frequently asked questions
Does this account for daylight saving time?
Yes — it uses the actual time zone rules for the date you enter, not just today's offset, so a conversion in January and one in July for the same city can correctly come out an hour apart.
Where does the time zone data come from?
Your browser's built-in Intl time zone database (the IANA time zone database) — no external API call, and it's the same data your operating system uses.
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2026-09-01Update history
- 2026-09-01 Launched: time zone calculator using the browser's native Intl time zone database — accurate DST handling with no external library or API. Entirely client-side.