What the Unix timestamp converter does
Unix time counts the seconds since 1 January 1970 00:00:00 UTC. Databases, API responses, log lines and JWT claims such as exp store instants this way. The number does not depend on a time zone: the same instant has the same value in London and in Tokyo, and the zone only matters when you read it as a calendar date.
The tool does three jobs: it converts a timestamp to a date, converts a date and time in a chosen zone to a timestamp, and converts a list with one value per line. A live clock at the top shows the current Unix time in seconds and milliseconds; you can pause it and copy the value into the input with one click.
How to use
- Pick a mode: timestamp → date, date → timestamp, or batch.
- Type the timestamp. With the unit on “auto” it is guessed from the number of digits; choose the unit yourself when you know it.
- In date mode enter the day and time; seconds and fractions of a second are optional.
- Choose the time zone. The default is Europe/Istanbul; UTC, your browser's zone or any IANA name such as
America/New_Yorkalso work. - Copy the result as text or JSON, or download a CSV in batch mode.
Unit detection and conversion rules
Auto mode looks at the size of the integer part. All arithmetic uses BigInt at nanosecond precision, so 19-digit nanosecond values are never rounded by floating point.
| Absolute value | Assumed unit | Example |
|---|---|---|
| below 10¹¹ | seconds | 1700000000 |
| 10¹¹ – 10¹⁴ | milliseconds | 1700000000000 |
| 10¹⁴ – 10¹⁷ | microseconds | 1700000000000000 |
| 10¹⁷ and above | nanoseconds | 1700000000000000000 |
- The guess can be wrong: a millisecond value from before 1973 looks like seconds. Pick the unit manually in that case.
- Negative values are instants before 1970;
-1.5seconds is 1969-12-31T23:59:58.500Z. - Unix time ignores leap seconds; every day has 86,400 seconds, so 23:59:60 is rejected.
- Impossible calendar dates such as 2023-02-29 are errors instead of silently rolling over to the next day.
- A wall time skipped by a daylight saving change is an error; a time that happens twice resolves to the earlier instant and the warning names the later one.
- RFC 2822 and HTTP dates are only produced for years 1900–9999; the HTTP date is always in GMT.
Turkey time and UTC+3
Turkey did not turn its clocks back in autumn 2016 and has used UTC+3 all year since 7 September 2016, with no daylight saving time. Before that it used UTC+2 in winter and UTC+3 in summer. The tool converts historical dates with your browser's copy of the IANA time zone database: 15 January 2015 12:00 in Istanbul shows +02:00, while 15 January 2017 12:00 shows +03:00. Before 1910 the zone used local mean time, so offsets can include seconds.
Example and interpretation
Entering 1700000000 is detected as seconds. In UTC it is 2023-11-14T22:13:20Z; in Istanbul it is 2023-11-15T01:13:20+03:00, so it is still 14 November in UTC while the date has already changed in Turkey. The RFC 2822 form is Wed, 15 Nov 2023 01:13:20 +0300 and the HTTP date is Tue, 14 Nov 2023 22:13:20 GMT. The same instant is day 319 of the year and ISO week date 2023-W46-3, the Wednesday of week 46.
In batch mode every line is checked on its own; a bad line does not stop the others and is reported with its line number.
The year 2038 problem and the date range
A timestamp stored as a signed 32-bit integer tops out at 2147483647, which is 2038-01-19T03:14:07Z. Old C libraries, embedded devices and 32-bit database columns can overflow after that. The tool warns when your value falls outside the 32-bit range. JavaScript dates cover 100 million days on either side of 1970; values beyond that are rejected.
Limits and privacy
Conversions run in your browser and inputs are not sent to a server. Time zone rules come from the browser's built-in data, so a very recent legal change may be missing from an outdated browser. Relative time (“3 days ago”) is measured against the moment you convert and does not refresh by itself; month and year values are rounded using average lengths. Adding inputs to the share link is optional.
Frequently asked questions
Is my timestamp in seconds or milliseconds?
For present-day dates a seconds value has 10 digits and a milliseconds value has 13. Auto mode uses that magnitude; select the unit yourself if you expect something else.
Does a Unix timestamp depend on the time zone?
No. The number marks the same instant everywhere. The time zone only decides how that instant is shown as a local date and time.
Why does Istanbul show UTC+3 all year?
Turkey has stayed on UTC+3 without daylight saving since 7 September 2016. Winter dates before 2016 are shown as UTC+2.
Are negative timestamps valid?
Yes. Negative values are instants before 1 January 1970. Some older systems do not accept them, so check the target system before storing such dates.
Will the year 2038 problem affect me?
Systems that keep time in a signed 32-bit integer overflow after 19 January 2038. A 64-bit time_t and modern database types are not affected by that limit.