Go with the largest width screen you can so that you get a better closure. The screen will be 1/8" narrower than the width you order. Measure your door opening top, bottom, and middle to make sure that it will accommodate the wider size. Otherwise, you will need to go down to the next smaller width screen.
If you do get the screen and determine it is the wrong size, we will exchange it for you, no problem.
Please also look at the Install page
of our website to get a better idea of how the retractable screen door is installed.