Index / Time
Unix Timestamp Converter
A timestamp into a date, or a date into a timestamp, in seconds, milliseconds, microseconds or nanoseconds. The unit is worked out from how many digits you pasted, and the page says which one it picked.
From a timestamp
From a date
ISO 8601 order only:
2026-08-26,
2026-08-26 14:30, 2026-08-26T14:30:00.250.
A trailing Z or +05:30 is honoured and
overrides the zone below.
Used to read a typed date that carries no offset,
and to pick which zone the headline shows. Both zones are listed
below either way.
Local time
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Seconds
--
Milliseconds
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The same instant, written every way
How the timestamp is read, and what it cannot say
Unix time counts seconds since 1 January 1970, 00:00:00 UTC, and
it counts every day as exactly 86,400 seconds. Leap seconds are not in
it: the 27 that have been inserted since 1972 were each given the same
timestamp as the second before, so a Unix timestamp cannot name one.
That is the standard's behaviour, not a shortcut taken here, and it is
why a timestamp is not a count of the seconds that have actually
elapsed.
The unit is guessed from the number of digits, and the guess is printed with the answer. Up to 11 digits is read as seconds, 12 to 14 as milliseconds, 15 to 17 as microseconds, and 18 or more as nanoseconds. The rule works because 11 digits of seconds reaches the year 5138, so a longer number is almost never a second count. Set the unit explicitly if you are working with dates that far out.
The calendar arithmetic is done here, not by the browser's date parser. Days are converted to and from a year, month and day with the standard civil-calendar algorithm, on the proleptic Gregorian calendar — the Gregorian rules projected back before 1582, which is what every computer means by a date. The browser is asked for exactly one thing: the offset of your time zone at that instant, which is the only part it knows and this page does not.
Nanoseconds are built as digits, not arithmetic. A double stops counting whole numbers at 9,007,199,254,740,993, and a nanosecond timestamp for any date after 1970 is larger than that. The seconds and the fraction are held apart and joined as text, so no digit is lost.
The timestamp rows carry no thousands separators, because they are there to be copied into something else. Every other number on the page is grouped.
Anything past 2,147,483,647 seconds — 19 January 2038 — is beyond what a signed 32-bit time_t can hold, and the page says so when you cross it. Timestamps are clamped to ±8,640,000,000,000 seconds, which is the range a browser can still tell you the time-zone offset for.
The unit is guessed from the number of digits, and the guess is printed with the answer. Up to 11 digits is read as seconds, 12 to 14 as milliseconds, 15 to 17 as microseconds, and 18 or more as nanoseconds. The rule works because 11 digits of seconds reaches the year 5138, so a longer number is almost never a second count. Set the unit explicitly if you are working with dates that far out.
The calendar arithmetic is done here, not by the browser's date parser. Days are converted to and from a year, month and day with the standard civil-calendar algorithm, on the proleptic Gregorian calendar — the Gregorian rules projected back before 1582, which is what every computer means by a date. The browser is asked for exactly one thing: the offset of your time zone at that instant, which is the only part it knows and this page does not.
Nanoseconds are built as digits, not arithmetic. A double stops counting whole numbers at 9,007,199,254,740,993, and a nanosecond timestamp for any date after 1970 is larger than that. The seconds and the fraction are held apart and joined as text, so no digit is lost.
The timestamp rows carry no thousands separators, because they are there to be copied into something else. Every other number on the page is grouped.
Anything past 2,147,483,647 seconds — 19 January 2038 — is beyond what a signed 32-bit time_t can hold, and the page says so when you cross it. Timestamps are clamped to ±8,640,000,000,000 seconds, which is the range a browser can still tell you the time-zone offset for.