To find when you will be a specific number of days old, enter the value in the second item.

To find the number of days between your birthday and a specific date, modify the last date.

To find a birthday that corresponds to a particular KDay, change the last date and the number of days and recalculate.

Then click the button or hit Enter to update the information.

If you put in a bad date, such as December 44, 1999, it will be converted it to a good date, such as January 13, 2000.