What is a Unix Timestamp?
A Unix timestamp — also called Unix time, epoch time, or POSIX time — is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970, a moment known as the “epoch.” It is a single integer that pins down an exact instant in time without any reference to time zones, calendars, or formatting. Because it is just a number, it is trivial to store, compare, and do arithmetic on: subtract two timestamps and you immediately have the duration between them in seconds.
That simplicity is why Unix time is everywhere on the server side — in log files, API responses, database records, JWT expiry claims, and file metadata. The drawback is that a number like 1716100000 means nothing to a human. This converter bridges the gap: paste a timestamp to see a readable date, or pick a date to get its timestamp.
How to Use the Timestamp Converter
- To decode a timestamp: paste the numeric value into the timestamp field.
- Read the result in both your local browser time and UTC ISO format.
- To encode a date: enter a calendar date and time to get its Unix timestamp.
- Use the current live timestamp shown on the page as a reference for “now.”
- Copy whichever value you need into your code, query, or log analysis.
Seconds, Milliseconds, and Time Zones
The single most common source of confusion is the unit. The classic Unix timestamp counts secondsand is currently a 10-digit number. JavaScript's Date.now(), however, returns milliseconds — a 13-digit number. Feed a millisecond value into a tool expecting seconds and you will land in the year 56000-something; feed a second value into a tool expecting milliseconds and you land in 1970. This converter recognises both the 10-digit and 13-digit forms so you do not have to multiply or divide by 1000 yourself.
The second thing to keep straight is time zones. A Unix timestamp itself is always UTC — it has no time zone. The moment you display it as a date, a time zone is applied. This tool shows two results on purpose: your localtime, formatted for your browser's region, and the UTC ISO string, which is unambiguous and ideal for logs or sharing. When two team members in different countries debug the same event, the UTC form is the one they should compare. Note also that Unix time ignores leap seconds, which is what keeps the arithmetic clean.
Frequently Asked Questions
How do I tell seconds from milliseconds?
Count the digits. A current timestamp in seconds has 10 digits; in milliseconds it has 13. If a decoded date looks absurdly far in the future or stuck in 1970, you have the wrong unit.
What is the year 2038 problem?
Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038. Modern systems use 64-bit integers, which postpone the limit by billions of years, so it is mainly a concern for legacy software.
Why does the same timestamp show a different date for a colleague?
The timestamp is identical — only the displayed time zone differs. Compare the UTC ISO output instead of the local time to be sure you are looking at the same instant.
Is my input sent to a server?
No. All conversion runs in your browser using the native Date object. Nothing you enter is transmitted or stored.