Measure the width of the door opening at the top, middle, and bottom
Measure the height of the door opening on the left and right sides
Measure the depth of the door frame or jamb
Use the smallest width measurement
Use the smallest height measurement
Check whether the door opens inward or outward
Note the hinge side and handle side
Measure from the inside edge of the frame for an accurate fit
Record the measurements in width x height format
Verify the measurements before ordering or cutting the screen door