Is there a standard size of door frame (jamb)?
No, there is no standard size of door frame. The door jamb that you need is directly related to the width of the wall where you will be installing the jamb. Measure the width of the stud plus the drywall on both sides of the opening to determine what size jamb you need. Since 2 x 4 studs actually measure 1 ½” x 3 ½” , add two times your drywall thickness plus 3 ½”.
