A date written as a number
Select the source unit, Seconds or Milliseconds, then paste the timestamp. The familiar date comes first, followed by the computer values in seconds and milliseconds. AM/PM is the default; choose 24-hour time if you need it. For the reverse direction, choose Date to timestamp, then enter a date and time labeled UTC.
1,700,000,000 seconds is 2023-11-14T22:13:20.000Z. In familiar terms, that is November 14, 2023 at 10:13:20 PM UTC. The same instant is 1,700,000,000,000 milliseconds. When entering these values, leave out the commas. -0.001 seconds is the final millisecond of 1969 in UTC.
How Unix time is counted
Zero is January 1, 1970 at midnight UTC. This tool follows the ECMAScript time-value definition, counting milliseconds without leap seconds. Decimal seconds are parsed into integer milliseconds before conversion, avoiding rounding at the last digit.
The supported range is 0001-01-01T00:00:00.000Z through 9999-12-31T23:59:59.999Z. A timestamp outside it shows an error. No values are stored or put in the page address.
If you need to move whole calendar dates instead of convert an instant, use the Date calculator.