Is my timestamp sent anywhere?

No. The conversion happens entirely in your browser using the built-in JavaScript Date object. Nothing is uploaded to any server.

What is the difference between seconds and milliseconds?

Unix time is most often counted in seconds since 1 January 1970 UTC, but JavaScript and many APIs use milliseconds (1000× larger). Use the dropdown to tell the converter which unit your number is in.

Why does my local time differ from UTC?

UTC is the global reference time with no offset, while local time is shifted by your time zone and daylight saving. The tool shows both so you can compare them directly.

Unix Timestamp Converter

Convert Unix epoch timestamps to dates and back — UTC, local, ISO and relative.

Unix timestamp converter

Paste a Unix epoch value — in seconds or milliseconds — and instantly see the UTC, local, and ISO 8601 dates, plus a plain-English relative label like “3 hours ago”.

You can also convert in the other direction: pick any date and time and read off the matching epoch seconds and milliseconds. Everything runs in your browser, so nothing you type is ever uploaded.