Unix Timestamp Converter
Convert Unix timestamps to dates and back online for free — local time, UTC, and ISO 8601, with seconds and milliseconds always kept separate.
Your files are processed locally in your browser and are not uploaded to our servers.
How to use Unix Timestamp Converter
- 1
Switch between "Timestamp → Date" and "Date → Timestamp."
- 2
For a timestamp, choose whether it's in seconds or milliseconds, then convert to see local time, UTC, and ISO 8601.
- 3
For a date, pick it with the date/time picker to get both Unix seconds and milliseconds.
Common uses
- Reading a raw timestamp from a log file, database row, or API response as an actual date
- Converting a specific date into a timestamp for a script, query, or test fixture
- Double-checking whether a timestamp value is in seconds or milliseconds before using it
Supported formats and limitations
Accepts text, up to one file at a time.
- Seconds and milliseconds are always kept as an explicit, separate choice — this tool never silently guesses which one a pasted number is in, since a timestamp in the wrong unit is a common, hard-to-notice bug.
- Local time reflects your own device's time zone and clock settings.
Frequently asked questions
A 10-digit number is typically seconds (covers dates until the year 2286); a 13-digit number is typically milliseconds. This tool requires you to choose explicitly rather than guessing, since guessing wrong silently produces a wildly incorrect date.
Yes — local time, UTC, and ISO 8601 (which is always UTC) are shown as separate, clearly labeled results, so there's no ambiguity about which time zone you're looking at.
Yes — negative timestamps (dates before the Unix epoch) are handled correctly.
No. All conversion happens entirely in your browser using your device's own clock and date handling.