I have a couple smaller rulers that have the 1/2" on 2 sides and I can not tell you how many times I have cut my fabric wrong (I do a lot of my sewing late at night and often when I should be in bed!). I finally took the worst culprit (a 6 x 6 1/2) and put it with my crafting items so I use it with wood and foamcore not with fabric! For squaring up, I usually go to a larger square so I have a better overview of the block I am cutting (a 12" ruler for a 10 1/2" block).