Make sure that you measure from the left side of the window casement all the way to the right.
The end of your Tape Measure should be firm up against the side of the casement, and should end firmly against the other side of the casement.
This measurement is your window screen 'Width'.
Measure from the Top of the Window Casement to the Bottom of the Window Casement.
This measurement is your window screen 'Height'.
When measuring for your Crossbar, place the tape measure on the bottom of the window casement (as shown below) and measure to the middle of the window crossing.
For Direct Screws:
The measurements above should be all that is necessary to use direct screws. Just make sure there is enough overlap to screw into the window casement.
For EZ Brick Clips:
If you are installing your full screen with EZ Brick Clips, you need to adjust the above WIDTH measurement by subtracting about 1' (one inch).
For Casement Clips:
If you are installing your full screen with Casement Clips, you need to adjust the WIDTH measurement as follows:
(1) mark on your window casing where you are planning to install the casement clips. See the black dot on the left of the image (where the tape measure begins) as an example. A similar dot should be on the right side of the window as well.
(2) ensure that your tape measure is inside these markings when taking measurements.
Window Screen Resource Center
The resources below provide information and articles meant to educate and answer any questions you may have related to window screens.