Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates. Supports seconds and milliseconds precision.
How to Use
- Enter a Unix timestamp to convert to a human-readable date
- Or pick a date and time to convert to a Unix timestamp
- Toggle between seconds and milliseconds format
Frequently Asked Questions
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What is a Unix timestamp?
A Unix timestamp is the number of seconds that have elapsed since January 1, 1970 (UTC), also known as the Unix epoch. It is widely used in programming and databases.
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What is the difference between seconds and milliseconds timestamps?
Unix timestamps in seconds are 10 digits (e.g., 1700000000), while millisecond timestamps are 13 digits (e.g., 1700000000000). JavaScript uses milliseconds, while most Unix systems use seconds.
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What is the Y2K38 problem?
32-bit systems store timestamps as a signed 32-bit integer, which will overflow on January 19, 2038. Modern 64-bit systems do not have this limitation.
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Does this tool account for time zones?
The tool displays times in both UTC and your local time zone for easy comparison.
What Is a Unix Timestamp?
A Unix timestamp is a single integer representing a point in time — specifically, the number of seconds elapsed since January 1, 1970, 00:00:00 UTC, a reference point known as the Unix epoch. This date was chosen somewhat arbitrarily by the designers of early Unix systems, but it has since become the universal standard for representing time in computing.
The simplicity of the Unix timestamp is its greatest strength: a single integer can represent any point in history (or the future) without ambiguity across time zones, locales, or calendar systems.
Seconds vs. Milliseconds
The original Unix timestamp counts in seconds, giving a 10-digit number for dates after 2001 (e.g., 1700000000). Many modern programming environments — JavaScript in particular — use milliseconds instead, producing a 13-digit number (e.g., 1700000000000).
This discrepancy is a common source of bugs. If a timestamp-based calculation produces a date in 1970 or a date 50,000 years in the future, you almost certainly have a seconds/milliseconds mismatch.
Quick rule: 10 digits = seconds, 13 digits = milliseconds.
Common Use Cases
Database storage: Timestamps are often stored as integers in databases (especially in high-performance systems) because integer comparison and sorting is faster than parsing date strings.
API design: Unix timestamps are unambiguous across time zones. A date string like "2024-01-15 09:00" is ambiguous without knowing the timezone; a Unix timestamp is always UTC.
Log analysis: Logs typically record Unix timestamps for precise, sortable event ordering.
Cache expiry: HTTP caches and session tokens often express expiry as a Unix timestamp.
The Y2K38 Problem
32-bit systems store Unix timestamps as a signed 32-bit integer. This value will overflow on January 19, 2038 at 03:14:07 UTC, rolling back to a large negative number representing the year 1901. This is the "Y2K38" problem — analogous to the Y2K bug but affecting 32-bit time representations.
All modern 64-bit systems are immune, as a 64-bit signed integer can represent dates hundreds of billions of years into the future. Most software has already migrated to 64-bit timestamps, but some embedded systems and legacy code may still be vulnerable.