Unix Timestamp Converter

Paste a Unix timestamp in seconds or milliseconds to see it as a UTC date, your local time, an ISO 8601 and RFC 3339 string and an HTTP date. Or type a date and get the timestamp back. It also warns you when a value will not fit in a signed 32-bit integer, the limit behind the year 2038 problem. Everything runs in your browser.

What a Unix timestamp is

A Unix timestamp counts the seconds since 00:00:00 UTC on 1 January 1970, called the Epoch. POSIX defines it as "seconds since the Epoch" and counts every day as exactly 86,400 seconds, so leap seconds are not included. A timestamp has no time zone: the same number means the same instant everywhere, and only the way you display it depends on the zone.

Seconds, milliseconds and more

• Seconds (10 digits today, such as 1700000000) are what Unix time, most databases and many APIs use.
• Milliseconds (13 digits, such as 1700000000000) are what JavaScript Date.now() and Java use.
• With the unit on Auto, a value of 12 or more digits is read as milliseconds and anything shorter as seconds. Set the unit yourself for very old dates in milliseconds or very distant dates in seconds. Microsecond and nanosecond values need dividing by 1,000 or 1,000,000 first.
• Negative values are dates before 1970. POSIX leaves them undefined, but most systems and this page handle them as ordinary calendar dates. Years 0000 to 9999 are supported.

Date formats

• ISO 8601 and RFC 3339. RFC 3339 is a profile of ISO 8601 for internet protocols. A date-time looks like 2023-11-14T22:13:20Z, or with an offset, 2023-11-15T03:43:20+05:30. Z means UTC. When you type a date without Z or an offset, the page reads it in the zone you choose.
• HTTP date. The fixed format used in HTTP headers, such as Tue, 14 Nov 2023 22:13:20 GMT (RFC 9110, section 5.6.7).

Well-known timestamps

The year 2038 problem

Older systems store time as a signed 32-bit integer (a 32-bit time_t). The largest value it can hold is 2,147,483,647, which is 03:14:07 UTC on 19 January 2038. One second later the number overflows and wraps to -2,147,483,648, which reads as 20:45:52 UTC on 13 December 1901. Systems that store time in 64 bits are not affected, and a 64-bit count of seconds lasts for billions of years. The risk sits in old embedded devices, file formats, databases and code that still use 32-bit fields, and in software that reads dates far in the future, such as a 30-year certificate or loan. Systems that treat the value as unsigned last until 2106. The converter flags any value outside the signed 32-bit range.

Study and related tools

Time handling and logs come up in system administration and security work. See the Linux commands cheat sheet, the Security+ SY0-701 objectives guide, the free Linux+ XK0-006 practice test, the JWT decoder, which shows a token's exp, iat and nbf times as dates, and the free tools page.

Unix timestamp FAQ

How do I get the current Unix timestamp?
Press "Use the current time". In a shell, date +%s prints it, in JavaScript Math.floor(Date.now() / 1000) and in Python int(time.time()).

Is a Unix timestamp in UTC?
It is independent of time zones. It counts seconds since the Epoch, which is defined in UTC. Converting it to a date in UTC or in your local zone is only about display.

Do Unix timestamps include leap seconds?
No. POSIX counts every day as 86,400 seconds, so a leap second does not get its own number.

Why is my timestamp 1000 times too big?
It is in milliseconds. Divide by 1,000 for seconds, or leave the unit on Auto.

What happens in 2038?
Only systems that keep time in a signed 32-bit integer overflow. See the section above.

Epoch definition: POSIX.1-2024 Base Definitions, section 4.19 "Seconds Since the Epoch" (pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap04.html). Formats: RFC 3339, Date and Time on the Internet (rfc-editor.org/rfc/rfc3339) and RFC 9110 section 5.6.7 (rfc-editor.org/rfc/rfc9110), checked on 8 November 2026. Results were tested on 8 November 2026 against known values and Python's datetime module, in three time zones.