Unix Timestamp Converter

Free Unix Timestamp Converter

Convert between Unix timestamps and human-readable dates instantly. This tool supports both seconds and milliseconds, UTC and local time, with ISO 8601 output and relative time descriptions. Whether you're debugging API responses, analyzing log files, or working with database timestamps, this converter handles it all.

What Is a Unix Timestamp?

A Unix timestamp (also called Epoch time, POSIX time, or Unix Epoch) is the number of seconds that have elapsed since January 1, 1970, 00:00:00 UTC — a moment known as the Unix Epoch. This system was introduced with the Unix operating system in the early 1970s and has since become the universal standard for representing time in computing.

Unix timestamps are used in virtually every backend system, database, and API because they are timezone-independent (always UTC-based), easy to compare and sort (simple integer comparison), compact (a single number), and unambiguous (no date format confusion like MM/DD vs DD/MM).

Seconds vs Milliseconds

Traditional Unix timestamps use seconds (10 digits, e.g., 1700000000), but JavaScript's Date.now() and many modern APIs use milliseconds (13 digits, e.g., 1700000000000). This converter supports both formats and auto-detects which one you're using based on the digit count.

Real-World Use Cases

• API Debugging — Many REST APIs return timestamps as Unix integers. Convert them to dates to verify token expiration, event timing, and data freshness.
• Log Analysis — Server logs, application logs, and system events often use Unix timestamps for precision and sortability. Convert them to readable dates for investigation.
• Database Queries — PostgreSQL, MySQL, and MongoDB store timestamps in various formats. Convert between them when writing queries or migrating data.
• JWT Token Inspection — JWT tokens use Unix timestamps for iat (issued at), exp (expiration), and nbf (not before) claims.
• Cron Job Scheduling — Verify when scheduled tasks ran or will run by converting timestamps from job logs.

The Year 2038 Problem

Systems storing Unix timestamps as 32-bit signed integers will overflow on January 19, 2038, at 03:14:07 UTC — the maximum value a 32-bit signed integer can hold (2,147,483,647). This is similar to the Y2K problem. Modern 64-bit systems are unaffected and can represent dates billions of years into the future. However, legacy embedded systems, IoT devices, and some databases still use 32-bit timestamps.

100% Private

All conversions happen in your browser using JavaScript's built-in Date object. No data is sent anywhere.

Frequently Asked Questions

Can I convert negative timestamps?

Yes. Negative Unix timestamps represent dates before January 1, 1970. For example, -86400 represents December 31, 1969. This tool handles negative values correctly.

Why does my timestamp show a different date than expected?

The most common cause is a seconds vs milliseconds mismatch. A 10-digit number is seconds; a 13-digit number is milliseconds. Also check whether your source uses UTC or local timezone — this tool displays both for comparison.

How do I get the current Unix timestamp in my code?

JavaScript: Math.floor(Date.now() / 1000). Python: import time; int(time.time()). PHP: time(). Ruby: Time.now.to_i. Bash: date +%s.

What is ISO 8601 format?

ISO 8601 is an international standard for date/time representation: 2026-04-02T12:30:00Z. The "T" separates date and time, and "Z" indicates UTC. It's unambiguous, sortable, and widely used in APIs and data interchange.