Time Zone Converter
Convert and compare a date-time string between any two time zones.
Paste an ISO 8601 formatted date, select the source and destination time zones, and instantly see the converted result.
This tool is useful for scheduling meetings across regions, verifying timestamps in logs or APIs, and checking time differences when working with global services.
The default comparison uses UTC and JST, but you can freely switch to any supported time zone.
All conversions are performed locally in your browser.
No date values are sent to any server, ensuring fast performance and privacy-safe usage.
UTC and JST Time Zone Converter
Cloud services, CI systems, logs, APIs, and databases often store or display time in UTC. This converter helps translate UTC to JST and other time zones so you can compare server events with local business hours, user reports, and release schedules.
When it helps
- Investigate incidents: Convert UTC log times into local time while matching alerts and user reports.
- Plan releases: Compare CI/CD schedules, maintenance windows, and regional deployment times.
- Review API data: Understand ISO 8601 timestamps and UTC-based fields in application responses.
Time zone note
Japan Standard Time is UTC+9 and does not use daylight saving time. Other regions may shift depending on the date, so always consider the date when converting between UTC and local time zones.
Articles for this tool
UTC to JST Reference: The 9-Hour Offset, Cheat Sheet & Timezone Pitfalls
Convert between UTC and JST (Japan Standard Time) with a cheat sheet. Covers what Z and +09:00 mean in ISO 8601, when JavaScript date parsing silently shifts by 9 hours, MySQL/PostgreSQL timezone behavior, and why GitHub Actions cron always runs in UTC.
How to Convert Milliseconds, Seconds, Minutes, and Hours for Timeouts and TTLs
Convert time units for API timeouts, cache TTLs, retry delays, polling intervals, and monitoring settings without mixing up milliseconds and seconds.
Unix Time and Timezones: A Practical Engineering Reference
Master Unix timestamps — what they are, the seconds vs milliseconds trap, timezone handling in JavaScript, Python, Go, and SQL, the 2038 problem, and how to convert them reliably.
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UTC to JST Reference: The 9-Hour Offset, Cheat Sheet & Timezone Pitfalls
Convert between UTC and JST (Japan Standard Time) with a cheat sheet. Covers what Z and +09:00 mean in ISO 8601, when JavaScript date parsing silently shifts by 9 hours, MySQL/PostgreSQL timezone behavior, and why GitHub Actions cron always runs in UTC.
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