What is a Unix Timestamp?
A Unix timestamp (also called Unix time, POSIX time, or epoch time) is the number of seconds that have elapsed since 00:00:00 UTC on January 1, 1970 — a point in time called the Unix epoch. It is a single integer that uniquely identifies any moment in time, making it ideal for storing, comparing, and calculating with dates in software.
Unix timestamps are timezone-independent. A timestamp of 1700000000 represents the exact same moment in time everywhere in the world — your local timezone only affects how it is displayed, not its value.
Seconds vs Milliseconds
Most Unix systems and APIs use seconds (10-digit timestamps around 1.7 billion). JavaScript and many web APIs use milliseconds (13-digit timestamps around 1.7 trillion). This tool supports both — use the s/ms toggle to switch. A common bug is accidentally treating a millisecond timestamp as seconds, which produces dates in the year 2527.
Common Use Cases
- API debugging — REST APIs often return timestamps as Unix integers. Paste one here to see what date it represents.
- Database inspection — Many databases store
created_atandupdated_atas Unix timestamps for efficiency. - Log analysis — Server logs frequently use Unix timestamps. Convert them to human-readable dates for troubleshooting.
- Scheduling — Calculate the Unix timestamp for a future date to use in cron jobs, event scheduling, or token expiration.
Frequently Asked Questions
What is the Unix epoch?
The Unix epoch is January 1, 1970, 00:00:00 UTC — timestamp 0. It was chosen somewhat arbitrarily when Unix was being developed in the late 1960s and early 1970s. All Unix timestamps are measured relative to this moment.
What is the Year 2038 problem?
32-bit signed integers can store a maximum value of 2,147,483,647, which corresponds to January 19, 2038, 03:14:07 UTC. Systems that store timestamps as 32-bit integers will overflow on this date. Modern systems use 64-bit integers, which won't overflow for billions of years.
Does this tool account for timezones?
Unix timestamps are always UTC. When converting a date string to a timestamp, whether your local timezone is applied depends on the format. A bare date like 2024-01-15 is interpreted as UTC midnight by most parsers. Appending a timezone like 2024-01-15T10:00:00+05:30 gives a precise, timezone-aware result. The "Local" display shows the timestamp converted to your browser's timezone.