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, 00:00:00 UTC — a moment in time known as the Unix Epoch. It is an integer, always increasing, and completely timezone-independent, which makes it the universal standard for timestamping events in software systems.
When a database stores a record's creation time, when an API returns a token expiry, when a log file records an error — they almost always use Unix timestamps under the hood. Knowing how to read and convert them is a fundamental skill for any developer.
Seconds vs Milliseconds
Two conventions exist. Unix timestamps in seconds are 10 digits long and used by most server-side systems (Python, PHP, Unix shell, databases). Timestamps in milliseconds are 13 digits long and are the default in JavaScript's Date.now() and most browser APIs. This converter auto-detects which format you've entered.
Common Timestamp Formats Explained
1717632000Seconds since epoch. Platform-universal, no timezone, compact.
2026-06-09T12:00:00.000ZInternational standard. Used in JSON APIs, HTML datetime, and database VARCHAR columns.
Tue, 09 Jun 2026 12:00:00 +0000Email and HTTP header standard. Used in Content-Date and email headers.
Tue, 09 Jun 2026 12:00:00 GMTHuman-readable UTC time. Good for logging and display.
3 days agoHuman-friendly relative difference from now. Common in social UIs.