Unix Timestamp Converter
Convert Unix/epoch timestamps to human-readable dates and back. Runs in your browser — nothing is sent to any server.
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Browse All Tools →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. It is a widely used standard for representing points in time in computing, databases, APIs, and log files. The Unix epoch serves as a universal reference point, making it easy to perform date arithmetic and compare timestamps across time zones.
Seconds vs. Milliseconds
Traditional Unix timestamps are measured in seconds, but many modern languages and APIs (such as JavaScript’s Date.now() and Java’s System.currentTimeMillis()) return timestamps in milliseconds. This tool auto-detects the format: values greater than 1012 are treated as milliseconds, while smaller values are treated as seconds.
How This Tool Works
Enter a Unix timestamp and instantly see it converted to your local time zone, UTC, ISO 8601 format, and a human-readable relative time like "3 hours ago." You can also pick a date and time to convert back to a Unix timestamp in both seconds and milliseconds. All processing runs entirely in your browser using the JavaScript Date API — no data is sent to any server.
The Year 2038 Problem
32-bit systems store Unix timestamps as a signed 32-bit integer, which will overflow on January 19, 2038, at 03:14:07 UTC. This is known as the Y2038 problem. Modern 64-bit systems and this tool use 64-bit representations, so they can handle dates far beyond 2038 without issue.
Frequently Asked Questions
Is my data safe?
Yes. All conversions happen entirely in your browser. No data is ever sent to a server. You can verify this by disconnecting from the internet and using the tool offline.
How does auto-detection work?
If the entered number is greater than 1012 (one trillion), it is treated as milliseconds. Otherwise, it is treated as seconds. This heuristic works correctly for all dates between 1970 and the year 33658.
Can I convert negative timestamps?
This tool currently supports only non-negative timestamps (dates from January 1, 1970, onwards). Negative timestamps represent dates before the Unix epoch, which are less common in most applications.
What time zone is used?
The "Local Time" output uses your browser’s time zone. UTC and ISO 8601 outputs are always in Coordinated Universal Time. Unix timestamps themselves are always UTC-based.