Unix timestamp converter
Convert Unix timestamps, dates, UTC, local time and ISO 8601.
How to use
A Unix timestamp is the number of seconds since 1 January 1970 at 00:00:00 UTC, the Unix epoch. It identifies the same instant everywhere in the world: time zones only come in when the instant is shown as a date. Leap seconds are not counted, so every day is exactly 86,400 seconds long.
Timestamp → Date: enter the number and choose seconds or milliseconds. The result shows the instant in ISO 8601 (in UTC, ending in Z), in the local time of your device and in UTC. Negative numbers are dates before 1970.
Date → Timestamp: choose a date and time and get the timestamp in seconds (rounded down) and in milliseconds. The date and time you choose are read as local time on your device, so the same entry gives different timestamps in different time zones.
In seconds, every date from 9 September 2001 to 20 November 2286 has ten digits; in milliseconds the same dates have thirteen. JavaScript's Date.now() and Java's System.currentTimeMillis() return milliseconds; the Unix date +%s command and PHP's time() return seconds. A date in January 1970 when you expected today means a value in seconds was read as milliseconds; a date tens of thousands of years in the future means milliseconds were read as seconds.
Systems that store the timestamp as a signed 32-bit number can count only up to 19 January 2038 at 03:14:07 UTC (2147483647) and overflow one second later, the year 2038 problem. This converter uses the browser's date range, which reaches the year 275760.
Example
1704067200 seconds corresponds to 2024-01-01 at 00:00:00 UTC. Local time depends on the device time zone.
17040672001 January 2024 at 00:00:00 UTC (seconds).1704067200000The same instant expressed in milliseconds.10000000009 September 2001 at 01:46:40 UTC, the first ten-digit timestamp.214748364719 January 2038 at 03:14:07 UTC, the largest value a signed 32-bit number can hold.-8640031 December 1969 at 00:00:00 UTC, one day before the epoch.
Frequently asked questions
Why is the local time different from UTC?
UTC is a global reference; local time applies the time-zone offset and daylight-saving rules of your device.
Does a timestamp have a time zone?
No. A timestamp is an instant, the same everywhere. 1704067200 is midnight on 1 January 2024 in London and 7 pm on 31 December 2023 in New York.
Why does Date → Timestamp give a number I did not expect?
The date and time you enter are read in your device's time zone. If you meant a time in UTC, the result is off by your UTC offset.
What happens to leap seconds?
Unix time ignores them: it assumes 86,400 seconds per day. When a leap second is added, the same timestamp covers two seconds, so the conversion cannot show 23:59:60.