Unix timestamp converter
Convert Unix timestamps in seconds or milliseconds to readable ISO 8601 dates in a time zone, and ISO dates back to Unix time.
- Runs in your browser
- No upload
- Result stays on your device
Privacy & limitsRuns in your browser. Nothing is uploaded.
Input content stays in this tab; Refentra does not upload or store it. Optional aggregate action counts are sent only with your usage consent. Clear the workspace when finished.
Supported profile: Unix seconds/milliseconds ↔ ISO with explicit offset; IANA zone; millisecond precision. ISO input needs seconds, up to three fractional digits and an explicit offset. Invalid calendar dates are rejected.
Maximum text: 200,000 UTF-16 units; parser limits can be smaller. Worker time limit: 15 seconds (regex 1.5 seconds).
Check the input and the result
- Prepare and choose the operation
Choose seconds, milliseconds or ISO input explicitly. Select the timezone for display, not for interpreting the input.
- Check a concrete example
Use this sample and compare the indicated result: 0 seconds → 1970-01-01T00:00:00.000Z; 1000 milliseconds → 1970-01-01T00:00:01.000Z
- Check the output before you reuse it
Compare the UTC ISO output with the display in the selected zone. They describe the same instant with different clock labels.
Answers for this task
Can a timezone-less date be converted?
Use ISO with seconds and an explicit Z or offset. The tool won't guess your local timezone.
What should I check if the input fails?
Check the units before you change any digits. Impossible calendar dates are rejected. Seconds allow at most 3 decimal places, and milliseconds must be integers.
Where does this tool stop?
This converts single instants, not recurring appointments. Daylight-saving rules affect the local time shown and may change when the timezone data changes.