Convert Unix timestamps to readable dates, or any date to a Unix timestamp.
What is a Unix Timestamp?
A Unix timestamp is the number of seconds (or milliseconds, in many modern systems) that have elapsed since January 1, 1970, at 00:00:00 UTC — a moment known as the Unix epoch. Unix timestamps are a universal, time-zone-neutral way to represent a precise point in time as a single integer, making them ideal for computing, databases, and data exchange between systems.
The converter on daycalctools.com works in both directions. You can paste a Unix timestamp and see the equivalent human-readable date and time in your local time zone, or enter a date and time to get the corresponding Unix timestamp in both seconds and milliseconds. All conversions are instant and run entirely in your browser.
Where Are Unix Timestamps Used?
Unix timestamps appear constantly in software development and data systems:
- Server logs — Web servers, databases, and APIs often store log entries with a Unix timestamp for compactness and precision.
- Database records — Many SQL and NoSQL databases store dates as Unix timestamps for efficient sorting and querying.
- API responses — REST and GraphQL APIs frequently return dates as Unix timestamps to avoid time zone ambiguity.
- File systems — File modification times (mtime), access times (atime), and creation times are stored as Unix timestamps at the OS level.
- Debugging — Developers use this tool to translate cryptic timestamps in logs into readable dates while troubleshooting issues.
- Blockchain and Web3 — Smart contracts and blockchain transactions use Unix timestamps to record when events occur on-chain.
Frequently Asked Questions
What is the Unix epoch?
The Unix epoch is the reference point from which Unix time is measured: January 1, 1970, at midnight UTC (00:00:00 UTC). All Unix timestamps represent the number of seconds (or milliseconds) elapsed since this moment. The choice of 1970 was a practical decision made by early Unix developers — it was the recent past at the time the system was designed.
What is the difference between seconds and milliseconds timestamps?
A Unix timestamp in seconds is the traditional format used by Unix/Linux systems and many programming languages. A millisecond timestamp is 1000× larger and is used by JavaScript (Date.now()), Java, and many modern APIs for sub-second precision. If you receive a 13-digit timestamp, it is almost certainly in milliseconds; a 10-digit timestamp is in seconds.
What is the Year 2038 problem?
Many older 32-bit systems store Unix timestamps as signed 32-bit integers, which can represent values up to 2,147,483,647 — equivalent to January 19, 2038 at 03:14:07 UTC. After this point, the counter overflows and wraps to a negative value, potentially causing software failures. Modern 64-bit systems do not have this problem, as they can represent timestamps billions of years into the future.
Are Unix timestamps affected by time zones?
No. Unix timestamps are always measured from the UTC epoch and have no time zone offset. The same timestamp represents the same point in time everywhere in the world. When the converter displays the human-readable date for a timestamp, it shows it in your local time zone — but the underlying timestamp value is the same regardless of where you are.
Can Unix timestamps represent dates before 1970?
Yes. Dates before January 1, 1970 are represented as negative Unix timestamps. For example, January 1, 1960 has a negative timestamp of −315,619,200 seconds. Most modern systems and programming languages correctly handle negative Unix timestamps for historical dates.