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Timestamp Converter

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What is a UNIX timestamp?

A UNIX timestamp is the number of seconds since 1970-01-01 00:00:00 UTC (the Unix epoch). It’s widely used in APIs, logs, databases, and event systems.

Some systems use milliseconds instead of seconds. This tool detects common formats and helps you convert UNIX timestamps to ISO 8601 dates and back — locally in your browser.

How to use the Timestamp Converter

  1. Paste a UNIX timestamp into the first field (seconds or milliseconds).
  2. Click “→ ISO” to convert it to an ISO 8601 date (UTC).
  3. Paste an ISO date into the second field.
  4. Click “→ UNIX” to convert it back to a UNIX timestamp.

Tips and common pitfalls

  • 10 digits usually means seconds; 13 digits usually means milliseconds.
  • ISO strings ending with “Z” are in UTC; offsets like +02:00 mean local time zones.
  • If your time looks wrong by hours, it’s usually a timezone/offset issue.
  • Some systems store timestamps as strings; make sure there are no spaces or commas.

Timestamp Converter FAQ

Seconds vs milliseconds — how do I know?
Most UNIX timestamps are 10 digits (seconds). 13 digits typically means milliseconds.
Is the ISO output in UTC?
Yes. ISO strings with “Z” are UTC. If you need a local timezone, convert after you get the ISO value.
Do you store my timestamps?
No. Conversions run in your browser. We don’t store or transmit your input.
Can I convert dates with timezone offsets?
Yes. ISO 8601 can include offsets (e.g., 2026-02-19T12:00:00+02:00). The tool converts it to a UNIX timestamp accordingly.