It’s amazing how many different sizes of sanding sheets you need in the shop. To simplify things, I made a jig that eliminates the measuring and can be configured to cut various sizes to fit your sanders and sanding blocks.
A spring-loaded, hinged panel holds the sandpaper flat and acts as a straight edge for cutting. Removable bolts placed in holes positioned on the board create stops to cut each size of sandpaper. You can write notes and labels on the plywood for each size you need to cut.