I like to mark and cut my bias binding from a square of fabric. I just use my large square ruler to mark the 45* angle starting on the bottom edge. I then use a longer ruler to extend that mark to the top edge of the square. I measure and cut 2 and 1/4 inch strips at the 45* angle. I use the longest strips and I just join them as needed. This allows me to shorten a strip if the next join would be in a bad spot.