Unix Timestamp Converter
Convert Unix timestamps to human-readable dates and vice versa, with timezone support.
What Is a Unix Timestamp?
A Unix timestamp (also called POSIX time or Epoch time) is a system for describing a point in time as the number of seconds elapsed since January 1, 1970, 00:00:00 UTC — known as the Unix Epoch. It is widely used in computing because it provides a simple, language- and timezone-agnostic way to represent a moment in time.
Modern systems often work in milliseconds (multiply seconds by 1,000) to allow for sub-second precision — common in JavaScript, Java, and many APIs. This tool handles both formats automatically via the Seconds / Milliseconds toggle.
How to Use This Tool
- Live clock — the current Unix timestamp in both seconds and milliseconds is shown at the top and updates every second.
- Timestamp → Date — paste any Unix timestamp into the left input. Toggle the switch for milliseconds if needed. Results show UTC, your selected timezone, and ISO 8601.
- Date → Timestamp — pick a date and time in the right panel. The equivalent Unix timestamps (seconds & ms) are shown instantly.
- Timezone selector — choose any IANA timezone from the dropdown to adjust the human-readable output.
- Copy buttons — click any copy icon next to a result to copy it to your clipboard.
Common Use Cases
- Debugging API responses that return numeric timestamps
- Converting database log times or server error timestamps
- Scheduling cron jobs or setting cookie/token expiry times
- Cross-timezone date comparison for global applications
- Verifying JWT token
iatandexpfields - Converting timestamps in data exports (CSV, JSON logs)
Frequently Asked Questions
What is the Unix Epoch?
The Unix Epoch is the reference point for Unix time: January 1, 1970, 00:00:00 UTC. All Unix timestamps count seconds (or milliseconds) from this moment. Negative values represent dates before 1970.
How do I know if a timestamp is in seconds or milliseconds?
A 10-digit number (e.g. 1700000000) is almost certainly in seconds. A 13-digit number (e.g. 1700000000000) is in milliseconds. Timestamps in seconds cover dates from 1970 to the year 2038+, while millisecond timestamps will be much larger. The tool auto-detects based on digit count if you prefer — just use the toggle.
What is the Year 2038 problem?
32-bit systems store Unix time as a signed 32-bit integer, which overflows on January 19, 2038 at 03:14:07 UTC. Modern 64-bit systems are not affected and can represent dates hundreds of billions of years into the future.
Does Unix time account for leap seconds?
No. Unix time deliberately ignores leap seconds — every day is treated as exactly 86,400 seconds. This means Unix time is technically not perfectly synchronized with UTC during a leap second insertion, but for most practical purposes the difference is negligible.
Why do different programming languages give different timestamps?
Most differences come from units: C/PHP/Python use seconds, while JavaScript/Java use milliseconds by default. Always check the documentation. Timezone differences can also cause apparent discrepancies when converting to human-readable dates, even if the raw timestamp is identical.
Can I convert negative Unix timestamps?
Yes! Negative timestamps represent dates before January 1, 1970. For example, -86400 is December 31, 1969. This tool fully supports negative values in the timestamp input.