Unix timestamp converter
Convert Unix timestamps in seconds or milliseconds to dates and times in a chosen time zone, and back again.
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How units and time zones are handled
Auto detection treats decimals and 1–10-digit integers as seconds, 13-digit integers as milliseconds, and asks you to choose a unit for 11- or 12-digit integers. Enter a local date and time directly or use the picker; seconds and fractional seconds are optional. The browser time zone is used by default. When converting a timestamp, the time zone changes only the displayed local date and time. When converting a local date and time, the time zone determines the Unix value.
Frequently asked questions
How does automatic unit detection work?
Decimals and 1–10 digit integers are treated as seconds. Thirteen-digit integers are treated as milliseconds. Choose a unit for 11–12 digit values.
Which date format can I enter?
Enter a local date and time without a UTC offset, such as 2026-08-29T14:30. Seconds and up to nine fractional digits are optional, or use the picker.
How do the time zone options differ?
The browser time zone is the default and follows the clock rules configured on your device. Choose UTC offset to use a fixed value such as +00:00 or +09:00. An IANA zone such as America/New_York follows that region's clock-change rules.
Can daylight saving time make a Unix timestamp ambiguous?
No. A Unix timestamp identifies one instant. Ambiguity arises only when you convert a local date and time in a zone where clocks change: some local times are skipped, while others occur twice. The tool shows an error by default; choose the earlier or later result only if you want it resolved.