Epoch Milliseconds Converter

About this calculator

The Unix epoch is the reference point January 1, 1970, 00:00:00 UTC, and most systems count elapsed time since then in seconds — but JavaScript’s Date object (and by extension, browser APIs, Node.js, and many web-facing JSON payloads) counts in milliseconds instead, returned by calls like Date.now() and getTime(). This converter takes a millisecond timestamp and converts it to a readable UTC date, or takes a UTC date and converts it back to milliseconds, also showing the equivalent seconds-based epoch value that most other languages and Unix tools expect.

This conversion comes up constantly in web development and API debugging: a log entry or database record might store a millisecond epoch while a backend service or CLI tool expects seconds, and mixing the two up by a factor of 1000 is a common source of “why is this timestamp showing the year 48,000-something” bugs. Developers reach for this converter to quickly sanity-check a raw timestamp value from an API response, browser console, or log file.