I can honestly say I have never held my fabric up to square it. I use the factory fold on one side and fold the selvages towards it to make the fabric about 11 inches so I can cut it on my smaller matt. I could cut it at 22 inches with my 24 inch ruler but I find that harder to keep control of my ruler and rotary cutter that way. I put my 15 square along the new fold to get the correct and square position and then use my smaller ruler to make a garbage cut. A garbage cut is to take off any edges that are not straight. The next cut is the one for my pattern.