Timestamp Converter
Convert Unix timestamps to dates and vice versa.
Seconds or milliseconds — auto-detected
What is a Unix timestamp?
A Unix timestamp counts the seconds since January 1, 1970, 00:00:00 UTC — also called the Unix Epoch. It's the most widely used time representation in computing because it's timezone-agnostic, simple to store as an integer, and trivially comparable and sortable.
Seconds vs milliseconds
Different systems use different precisions. Most POSIX/Unix APIs use seconds. JavaScript, Java, and many modern APIs use milliseconds. PostgreSQL and MySQL store as seconds with optional fractional parts. Redis uses milliseconds. This tool auto-detects by checking if the value exceeds 10¹² (the approximate millisecond timestamp for the year 2001).
Common uses
- Debugging API responses with timestamp fields
- Verifying JWT expiry (exp claim)
- Reading database timestamps
- Checking log file timestamps
- Setting cache or cookie expiration
Frequently asked questions
- What is a Unix timestamp?
- A Unix timestamp is the number of seconds that have elapsed since the Unix Epoch — midnight UTC on January 1, 1970. It's a universal, timezone-independent way to represent a specific moment in time. It increases by 1 every second and is used in virtually every programming language and database.
- Seconds vs milliseconds — which does my system use?
- Most Unix systems and databases store timestamps in seconds (10 digits as of 2025: e.g. 1700000000). JavaScript's Date.now() returns milliseconds (13 digits: e.g. 1700000000000). This tool auto-detects: if the value is greater than 10^12, it assumes milliseconds.
- What is the maximum Unix timestamp?
- The Unix timestamp overflows a signed 32-bit integer at 2,147,483,647 — which corresponds to January 19, 2038 (the Y2K38 problem). Modern systems use 64-bit integers which extend the range billions of years into the future.
- What is ISO 8601?
- ISO 8601 is the international standard for date and time representation: YYYY-MM-DDTHH:mm:ss.sssZ. The Z indicates UTC. Example: 2024-11-14T22:13:20.000Z. It's unambiguous, sortable alphabetically, and universally understood by APIs and databases.
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