Unix Timestamp Converter: Epoch to Date, UTC and Local Time
Convert seconds/milliseconds timestamps into human readable dates, inspect live epoch clock, and run bulk conversions.
Unix timestamp: definition, date conversion and the 2038 problem
A Unix timestamp is the number of seconds elapsed since 1 January 1970 at 00:00:00 UTC, with every day counting exactly 86,400 seconds: leap seconds are ignored. 1740474000 is 25 February 2025 at 09:00:00 UTC, or 10:00 in Paris. The tool also recognises values in milliseconds, microseconds and nanoseconds from their number of digits.
What the tool does
- Live clock: current epoch in seconds, updated every second from the device clock.
- Timestamp to date: the unit is inferred from the input length: 11 characters or fewer = seconds, 12 to 14 = milliseconds, 15 to 17 = microseconds, 18 or more = nanoseconds. The result is shown as ISO 8601 UTC, RFC UTC format, browser local time and relative time (“3 days ago”).
- Date to timestamp: the date and time you enter are read either as UTC or in the browser’s local time zone; no other time zone can be selected.
- Batch conversion: one value per line, result as ISO 8601 UTC. Only two units are recognised here: 11 characters or fewer as seconds, longer values as milliseconds.
Examples
- 0 → 1970-01-01T00:00:00Z; 1735689600 → 2025-01-01T00:00:00Z.
- 14 October 2026 at 12:00:00 UTC → 1791979200 seconds, 1791979200000 milliseconds.
- 2147483647, the largest signed 32-bit integer → 2038-01-19T03:14:07Z.
The year 2038
A system that stores Unix time in a signed 32-bit integer overflows on 19 January 2038 at 03:14:08 UTC and wraps back to December 1901. The tool is not affected: JavaScript dates are 64-bit floating-point millisecond counts.
Limits
Unix time does not count leap seconds, so two instants separated by a leap second can share a timestamp. The local time shown depends on the time zone set on your device.
Sources and dates: definition of “seconds since the Epoch”, POSIX, IEEE Std 1003.1-2024, section 4.19 (each day counts as 86,400 seconds). (checked 14/10/2026)
Frequently Asked Questions
What is the Unix epoch?
It is the origin of Unix time: 1 January 1970 at 00:00:00 UTC, which equals 0. A timestamp counts the seconds since that instant, at 86,400 seconds per day.
How can I tell whether a timestamp is in seconds or milliseconds?
Today a timestamp in seconds has 10 digits (1791979200) and one in milliseconds has 13 (1791979200000). The tool treats 11 characters or fewer as seconds and 12 to 14 as milliseconds.
What happens on 19 January 2038?
At 03:14:07 UTC the timestamp reaches 2147483647, the largest signed 32-bit integer. One second later, systems still using that format overflow and show a date in December 1901.
Does a Unix timestamp depend on the time zone?
No, it refers to the same instant everywhere in the world. Only the display changes: 1740474000 reads 09:00 UTC, 10:00 in Paris and 04:00 in New York.
Are leap seconds counted?
No. POSIX counts every day as exactly 86,400 seconds, so the leap seconds added since 1972 do not appear in Unix time.
Is this tool really free?
Yes, all tools on Kristools are 100% free and accessible without registration.
Is my data protected?
Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.