Unix timestamp converter: seconds, milliseconds, UTC and local time

A Unix timestamp converter turns a number like 1700000000 into a date you can read, and turns a date back into that number. The free AyeTab Unix Time Converter shows seconds, milliseconds, ISO 8601, UTC, your local time and a relative time from one input, and it does the work in your browser.

What Unix time is

Unix time counts the seconds since midnight UTC on 1 January 1970, leaving out leap seconds. Databases, APIs, log files and JWT claims all use it because a single integer is easy to store, sort and compare. The catch is that nobody can read it. Is 1767225600 last week or next year? (It is the first second of 2026, UTC.)

Two variants cause most of the confusion:

• Seconds, usually 10 digits today. Unix shells, PHP, Python's time.time() (rounded) and most databases use these.
• Milliseconds, usually 13 digits. JavaScript's Date.now() and many event and analytics APIs use these.

Mix them up and a date lands in 1970 or tens of thousands of years in the future.

How the AyeTab converter works

The page has one field, labelled "Timestamp or date". Type or paste a value and the result cards fill in:

A 13-digit number is read as milliseconds; a 10-digit number as seconds. Anything else is read as a date, so pasting an ISO string gives you the timestamp in the other direction. The Now button fills in the current second, and clicking any card copies its value.

Why run it locally

Timestamps rarely travel alone. You copy them out of a production log line, a webhook body or a decoded token, and the text around them can be sensitive. When a converter runs on a server, whatever you paste can reach that server.

Every AyeTab tool runs in the browser tab. Nothing is uploaded and there is no account to create, so you can paste a line from a log without thinking twice.

The extension and the web app

You can use the converter at app.ayetab.com in any modern browser. If you convert timestamps a few times a day, the free AyeTab extension for Chrome puts the same tools on your new tab page and in a side panel. Ctrl+K (Cmd+K on a Mac) opens a command palette for jumping to the converter, favorites keep it at the top of the list, and the tools work offline once installed. For date arithmetic and time zone conversion beyond a single timestamp, the AyeTab Time Calculator sits in the same toolbox.

When another tool fits better

AyeTab's converter handles seconds and milliseconds. If your data holds microsecond or nanosecond values (16 or 19 digits), epochconverter.com reads those, and it also lists start and end timestamps for a year, month or day. For thousands of rows, convert in code or SQL instead of by hand.