Master Exterior Door Measurements
When purchasing your new exterior door, it’s a good idea to get up-to-speed on terminology and standard entry door measurements.
the size of the opening that a pre-hung door will fit into
Net Frame Dimension: the full width of the frame
Jamb Size: the depth of the frame, not the width, covering the sheathing or siding and wall stud
Masonry Opening: the space between the bricks on the front of your home as they surround the door (if applicable)
Though more expensive, you can also order a custom size door if your door opening is an unusual size. A better option might be to modify the existing frame opening if feasible.
Exterior doors are subject to the National Building Code, which stipulates that doors opening to the outside may not measure less than 32 inches wide and 75 inches high, though most common door heights are 80 inches or more. Municipalities may increase the required width and height stipulated in the Code but never decrease them. Doors that require wheelchair access must be a minimum of 36 inches wide.