Unix Timestamp Converter

How this timestamp converter works

Enter a Unix timestamp (seconds since January 1, 1970 UTC) or a human-readable date, and it converts between them instantly using your browser's built-in Date object — no server round-trip needed.

Seconds vs. milliseconds — the most common bug

Unix timestamps are conventionally in seconds, but JavaScript's Date object and many APIs (including JavaScript's own Date.now()) use milliseconds. Pasting a seconds-based timestamp into a tool expecting milliseconds (or vice versa) produces a date off by a factor of 1000 — usually landing somewhere in 1970 or far in the future. If your converted date looks obviously wrong, check whether the timestamp you have is actually in seconds or milliseconds.

Timezones and the Year 2038 problem

The underlying epoch is always UTC, but the human-readable display typically converts to your browser's local timezone unless the tool explicitly shows UTC — worth double-checking if you're coordinating across timezones. Separately, systems that store timestamps as a signed 32-bit integer will overflow on January 19, 2038 (the "Year 2038 problem"), similar in spirit to Y2K; most modern systems have moved to 64-bit timestamps, but older embedded or legacy systems may not have.