Time and dates

How to tell seconds from milliseconds in a timestamp

A chart or a token expiry looks a thousand times off. Compare the log with Unix Timestamp Converter and Epoch Now.

Ben Fidge · Oct 2026 · 5 min read

Ten digits are Unix seconds and thirteen are milliseconds. UTC and local are the same instant. — Ten digits are Unix seconds and thirteen are milliseconds, so a thousand-fold gap is a digit-length mismatch.

What to run

Open Unix Timestamp Converter and Epoch Now. Both stay in the browser.

How to read the result

Current epoch seconds is about 10 digits. Current milliseconds is about 13.

The converter prints both so you can match the log.

What to open next

Open JWT Decoder if the number came from an exp claim. exp is seconds. JWT Decoder does not verify the signature. It stays in the browser.