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Unix Timestamp Converter

Convert between Unix time and every common date format, with a live clock and batch mode.

Runs in your browserNo sign-up required

Every Format at Once, Plus Batch Mode

Rather than picking one output format ahead of time, this shows ISO 8601, UTC, RFC 2822, relative time, and your chosen time zone's local time simultaneously for whatever you paste in — and a batch mode below it for converting a whole list of timestamps in one pass instead of one at a time.

How to Use This Tool

  1. 1Paste a timestampSeconds, milliseconds, or microseconds — the unit is auto-detected from its length.
  2. 2Pick a target time zoneSee the converted result in UTC, your chosen city's time, plus ISO 8601, RFC 2822, and relative formats all at once.
  3. 3Copy any formatEach result row has its own copy button.
  4. 4Or batch-convertPaste a list of timestamps, one per line, for a quick table of results.

Good to Know

  • Unix time counts seconds (not milliseconds) since January 1, 1970 UTC by the original definition — JavaScript's Date.now() returns milliseconds instead, which is the single most common source of an "off by 1000" mistake.
  • The live clock at the top updates every second, showing the current timestamp in both seconds and milliseconds for quick reference.
  • Relative time ("in 3 hours", "2 days ago") is computed from the current moment, so it changes slightly each time you reload the page for a fixed timestamp.
  • Batch mode auto-detects each line's unit independently, so a mixed list of seconds and millisecond timestamps still converts correctly line by line.

Frequently Asked Questions

How does the tool know if I pasted seconds or milliseconds?

By the number of digits — a modern Unix second timestamp is 10 digits, milliseconds is 13, and microseconds is 16, so the length alone reliably distinguishes them for any date in the last several decades.

What's the difference between UTC and RFC 2822 format?

Both represent the same moment in UTC, just formatted differently — RFC 2822 is the format historically used in email headers (e.g. "Wed, 02 Oct 2024 15:00:00 GMT"), while the plain UTC string is JavaScript's default toUTCString() output.

Can I convert a date back into a Unix timestamp?

This tool converts from a timestamp forward into other formats. For the reverse direction, the Date Calculator among the Calculators tools covers date-to-date math, though a straightforward way is entering the date string directly into your own code's Date constructor.

Is this free to use?

Yes, completely free, with no limit on how many timestamps you convert.