About Unix timestamps
Seconds versus milliseconds
Unix time counts from 1970-01-01T00:00:00Z. Select seconds or milliseconds explicitly. Negative values represent dates before the epoch.
Timezone handling
Enter an ISO 8601 date with Z for UTC or an explicit offset such as +09:00. The result shows UTC and the local timezone configured in your browser.
Precision
Timestamp inputs must be integers. ISO input supports milliseconds; whole Unix seconds are rounded down, including for dates before the epoch. Leap-second values are not supported.