Unix timestamp to Date Converter – Free, Online, Private

Seconds, not milliseconds

A classic Unix timestamp counts seconds. 1700000000 is 10 digits and falls in 2023. Values with 13 digits are almost always milliseconds and will look like a date in the year 50000 if you interpret them as seconds. This page does not guess. If the number is too large to be a sensible second count, switch to the epoch milliseconds converter. Fractional seconds are accepted as a number but the ISO string shows millisecond precision only, because that is what the JavaScript Date can represent.

UTC and local

The UTC line is an ISO-8601 string with a Z suffix. That is the instant, independent of where you sit. The local line uses the timezone of the browser, which is what a log viewer on your laptop shows and what a server in UTC will not show. Do not paste the local line into a system that expects UTC. The output also echoes the normalized seconds and the millisecond form so you can copy whichever a library wants. Negative timestamps are dates before 1970 and are valid.

Worked example

1700000000 is 2023-11-14T22:13:20.000Z. The local line shifts by your offset. A timestamp of 0 is the epoch itself. A value pasted with quotes or a trailing ms label will fail; the box wants a number. The date to Unix page is the inverse: give it an ISO string and it prints seconds. Leap seconds are not represented. POSIX time ignores them, and so does Date.

Where this runs

The arithmetic is local. Timestamps are rarely secret, but the page is the same static tool as the others and does not log the value. For cron schedules rather than a single instant, use the cron to human page.

Frequently asked questions