The 'Call Size' (Size you ask for) on 'ALL Manufactired Houseing doors & windows' is the Rough Opening or the 'framed opening'
(2x4 to 2x4 , Floor or jamb to the header) in the house.
The easiest way to get the correct call size of a single outswing door is to measure the door (everything that moves) on the Outside.
That measurement is the Call Size
Standing Outside and looking at the door if the hinges are on the left it is a Left Hinge else it's a Right Hinge