I have a ruler that is actually 14" x 14". The cutting area is 12" x 12" with 1/2" slots for cutting. It has a diagonal
line from each corner that crosses in the middle. The only draw back with this ruler is that you have to put your finger on the part of the ruler close to where you are cutting (the slit befor the cut) to keep the plastic of the ruler from moving. But I have learned to do it right and I love it.