Epoch Converter
Convert Unix timestamps to human-readable dates and back.
Enter a Unix timestamp in seconds or milliseconds. Milliseconds are auto-detected.
What Is a Unix Timestamp?
A Unix timestamp (also called Epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC, not counting leap seconds. This single integer provides a universal, timezone-independent way to represent a moment in time, making it one of the most widely used time formats in computing. The "epoch" is simply the reference starting point — midnight on New Year's Day, 1970.
Why Do Developers Use Unix Timestamps?
Timestamps are a compact, unambiguous representation of time. Unlike human-readable dates that can be interpreted differently depending on locale (is 03/04/2025 March 4th or April 3rd?), a Unix timestamp is the same everywhere. They are trivial to compare, sort, and do arithmetic with — subtracting two timestamps gives you the exact number of seconds between two events. Databases, APIs, log files, JWT tokens, and event queues all rely heavily on epoch time for consistency.
Seconds vs. Milliseconds
The traditional Unix timestamp counts in whole seconds. Many modern platforms — including JavaScript's Date.now() and Java's System.currentTimeMillis() — use millisecond precision instead, resulting in a 13-digit number. This tool auto-detects which format you provide: if the value exceeds 10 trillion, it is treated as milliseconds and converted accordingly.
Common Conversions
Developers frequently need to translate timestamps into human-readable dates for debugging logs, verifying API responses, checking token expiration, or building time-based features. This converter outputs UTC and local dates, ISO 8601 strings, relative time descriptions, day of the week, and week of the year. Everything runs in your browser using the native JavaScript Date API — no data is sent to any server.