Measure the width of the door opening at the top, middle, and bottom
Use the smallest width measurement
Measure the height of the door opening on the left, middle, and right
Use the smallest height measurement
Measure the depth or thickness of the door frame if required by the screen door type
Check whether the door opens left-hand or right-hand
Check whether the door swings in or out
Measure from the outside edge of the frame to the opposite edge for the opening size
Verify that the threshold is level and note any uneven areas
Measure any trim, molding, or obstructions that may affect installation
Compare all measurements with the screen door manufacturer’s size requirements
Recheck all measurements before ordering or cutting the screen door