Leap years (366 days) to days converter on this page calculates how many days are in 'X' leap years (366 days) (where 'X' is the number of leap years (366 days) to convert to days). In order to convert a value from leap years (366 days) to days (from leap y to d) simply type the number of leap y to be converted to d and then click on the 'convert' button.