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Unix Timestamp Converter
Convert Unix epoch time to human-readable dates and back. Seconds and milliseconds supported.
Timestamp → date
Date → timestamp
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 — known as the Unix epoch. It's one of the most common time representations in computing because it's timezone-agnostic, sorts as a number, and fits in a small fixed-size integer.
For example, 1735689600 represents January 1, 2025 00:00:00 UTC. Many systems use milliseconds instead (1735689600000).
When you'll encounter Unix timestamps
- APIs and JSON: most REST APIs return timestamps as Unix seconds or milliseconds (Twitter, Stripe, GitHub, etc.).
- Databases: log files, event tables, expiration fields (
expires_at) often store epoch integers. - Authentication: JWT tokens use
iat(issued at) andexp(expiration) as Unix timestamps. - Programming:
Date.now()in JavaScript,time.time()in Python,DateTime.Now.ToUnixTimeSeconds()in .NET.
Seconds vs milliseconds
A 10-digit timestamp is in seconds (up to roughly year 2286). A 13-digit timestamp is in milliseconds. This tool auto-detects the format.
Rule of thumb: JavaScript's Date.now() returns milliseconds, while most Unix command-line tools and C libraries use seconds.