Unix timestamp converter
Paste an epoch timestamp – the converter works out whether it is in seconds, milliseconds, microseconds or nanoseconds and shows the date in UTC, in your time zone and in every common format. It also turns a date into a Unix timestamp.
Source: IEEE Std 1003.1, The Open Group Base Specifications (POSIX, IEEE Std 1003.1-2024) – 4.19 Seconds Since the Epoch. Updated: .
How it is calculated
A Unix timestamp (epoch time) counts the seconds since 1 January 1970, 00:00:00 UTC, the Unix epoch. That is how POSIX defines it (IEEE Std 1003.1, “Seconds Since the Epoch”): every day has exactly 86,400 seconds and leap seconds are not counted. The number is the same everywhere in the world – the time zone only matters when you display it.
How to convert a Unix timestamp
- Choose the direction: timestamp to date, or date to timestamp.
- Paste the timestamp (let the unit be detected automatically or set it yourself), or enter a date and time and say whether it is in UTC or a time zone.
- Read the result – the table lists every format, such as ISO 8601, ready to copy.
Example: The timestamp 1700000000 has 10 digits, so it is in seconds, and equals 14 November 2023 at 22:13:20 UTC – 5:13:20 PM in New York (UTC−5). In milliseconds the same moment is 1700000000000.
Seconds, milliseconds, microseconds, nanoseconds
Many systems store finer units: JavaScript (Date.now()) and Java return milliseconds, Python’s time.time_ns() and Go nanoseconds, PostgreSQL uses microseconds internally. The converter guesses the unit from the number of digits: up to 11 digits seconds, 12–14 milliseconds, 15–17 microseconds, 18–19 nanoseconds. Today a timestamp in seconds has 10 digits, in milliseconds 13. If the guess is wrong, pick the unit yourself.
Output formats
- ISO 8601 / RFC 3339:
2026-09-27T12:30:00.000Z– the standard for APIs and JSON;Zmeans UTC, otherwise an offset such as+02:00follows. - RFC 2822 / 5322:
Sun, 27 Sep 2026 14:30:00 +0200– the date line of an email. - RFC 7231 / 9110 (IMF-fixdate):
Sun, 27 Sep 2026 12:30:00 GMT– for HTTP headers such asDate,ExpiresorLast-Modified, always in GMT. - Local time: including daylight saving time, from your browser’s IANA time zone database.
The year 2038 problem
If Unix time is stored as a signed 32-bit integer, it tops out at 231 − 1 = 2,147,483,647 – 19 January 2038, 03:14:07 UTC. One second later the counter wraps to a negative number (13 December 1901). Modern operating systems use 64 bits; the risk lies in old embedded devices, file formats and database columns with 32-bit time. The converter warns you when a value crosses that limit.
Everything is calculated in your browser; nothing is sent anywhere.
More developer tools: read the time inside a UUID v7 with the UUID generator, check data with the JSON formatter and test patterns with the regex tester.
Frequently asked questions
What is a Unix timestamp?
The number of seconds since 1 January 1970, 00:00:00 UTC, ignoring leap seconds (POSIX). For example, 1700000000 is 14 November 2023, 22:13:20 UTC.
How can I tell seconds from milliseconds?
By the length: current timestamps have 10 digits in seconds, 13 in milliseconds, 16 in microseconds and 19 in nanoseconds. The converter detects this automatically.
Does a timestamp depend on the time zone?
No. A timestamp refers to the same instant everywhere. Only the displayed clock time depends on the time zone, which is why the tool shows UTC and local time side by side.
How do I get the current timestamp in code?
JavaScript: Math.floor(Date.now() / 1000); Python: int(time.time()); PHP: time(); Linux shell: date +%s; PostgreSQL: extract(epoch from now()).
What happens in 2038?
On 19 January 2038 at 03:14:07 UTC Unix time reaches 2,147,483,647, the largest value of a signed 32-bit integer. Systems with a 32-bit time_t overflow; 64-bit systems are good for about 292 billion years.
Are leap seconds taken into account?
No – just like POSIX and JavaScript. Unix time pretends every day has 86,400 seconds; system clocks smear or repeat a leap second instead.
Sources and legal basis
- IEEE Std 1003.1: The Open Group Base Specifications (POSIX, IEEE Std 1003.1-2024) – 4.19 Seconds Since the Epoch
- RFC 3339: RFC 3339 – Date and Time on the Internet: Timestamps (ISO 8601 profile)
- RFC 5322 §3.3: RFC 5322 – Internet Message Format, 3.3 Date and Time Specification (successor of RFC 2822)
- RFC 9110 §5.6.7: RFC 9110 – HTTP Semantics, 5.6.7 Date/Time Formats (IMF-fixdate, formerly RFC 7231 §7.1.1.1)
- ECMAScript (ECMA-262) – Time Values and Time Range
- ECMAScript Internationalization API (ECMA-402) – Intl.DateTimeFormat, Intl.RelativeTimeFormat
- IANA Time Zone Database
As of: · Editorial policy
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