Unix Timestamp Converter
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Paste a Unix timestamp and read it as a date, or paste a date and get the timestamp back. The field takes either, and works out which you gave it. It also works out whether a bare number is in seconds or milliseconds and says which it assumed, because that guess is the one thing a timestamp does not tell you and getting it wrong is fifty-three years out.
A number is read as a timestamp; anything else is read as a date. ISO 8601 works best.
Reading this as .
Frequently asked questions
How does it know whether my number is seconds or milliseconds?
By size. Anything at or above 100,000,000,000 is treated as milliseconds, and anything below it as seconds. That boundary is the year 5138 in seconds and 1973 in milliseconds, so it is nowhere near a date anyone is working with. The tool says which it read the number as, in a line under the field, and that line carries a dropdown for the rare number where the guess is wrong.
Why does the local time differ from the UTC line?
Because they are the same instant written in two places. The local line uses your computer’s own time zone, which the tool names on the same line so there is no doubt which one it used.
What date formats does it accept?
ISO 8601 such as 2023-11-14T22:13:20Z is read reliably. Other formats depend on your browser and may be read differently in different ones, so ISO is the safe choice. A date with no time zone is read as your local time, which is what someone typing their own clock’s reading means.
Is what I paste sent anywhere?
No. The conversion runs in your browser. The site’s security policy sets connect-src ‘none’, so the browser blocks network requests from these pages, meaning nothing could be sent even if the code tried.