Timezone Converter
Convert times between IANA timezones with DST handled.
Runs locally in your browser. Your input is not uploaded or stored. You can verify this in your browser’s network panel.
What does this tool solve?
Pick a date and time, choose the source and target IANA timezones, and get the same instant in both — with daylight saving handled by the browser's IANA database.
What examples should you start with?
UTC to Tokyo
Input
2025-01-15 00:00 UTC → Asia/Tokyo
Output
2025-01-15 09:00 (UTC+09:00)
US East Coast to London
Input
2025-01-15 12:00 America/New_York → Europe/London
Output
2025-01-15 17:00 (UTC+00:00)
How does it work?
The wall-clock time is interpreted in the source zone by resolving that zone's UTC offset at the guessed instant and refining once, so daylight-saving boundaries land correctly.
Formatting uses Intl.DateTimeFormat with the IANA timezone database built into your browser — the same data your operating system uses.
What are the edge cases and limits?
- During the spring-forward gap some wall times don't exist locally; the conversion still resolves to a coherent instant.
- DST rules change when governments change them — results follow the browser's IANA database version.
- The zone list covers ~30 common zones; the full IANA database has hundreds.
Technical reference
Related tools
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