⏱ Unix Timestamp Converter

Unix time is the number of seconds since 1970-01-01 00:00:00 UTC, ignoring leap seconds. Every database timestamp, JWT claim and log line is built on it, and almost every bug around it is the same one: seconds versus milliseconds. This page converts both ways, live, and shows which unit it assumed.

Timestamp → date

Date → timestamp

Right now, by time zone

The three traps in Unix time

Seconds vs milliseconds. JavaScript’s Date.now() returns milliseconds; Unix time, PHP and most databases use seconds. A 10-digit number is seconds (good until 2286), a 13-digit number is milliseconds — this page’s auto-detect uses exactly that rule and says which it chose. Leap seconds are not counted: Unix time pretends every day is exactly 86,400 seconds, so it has drifted 27 seconds from UTC since 1972 — irrelevant for logs, real for astronomy, and the reason tai exists. Time zones are not part of the number: a timestamp describes one instant on Earth; 09:00 in Tokyo and 02:00 in Berlin can be the same integer. Only the rendering has a zone — which is why “the timestamp looks wrong” is almost always a display problem, not a data problem.

Also worth knowing: the classic Year 2038 problem comes from 32-bit signed seconds running out on 2038-01-19; 64-bit systems are fine for ~292 billion years. Negative timestamps are legitimate — they mean dates before 1970, and this page converts them correctly.

Part of Everyday Tools. For calendar arithmetic (days between dates, exact age), use the date & age calculator.