She bases most of her stuff on precuts because that is what they sell. So, it is usually a good guess to start with 5" or 10" squares, 2 1/2" or 1 1/2" strips (charm packs, layer cakes, jelly rolls and honey buns). Whenever in doubt, draw the finished block to size on graph paper and cut it out. Sometimes the actual pieces in hand is so much easier than trying to sort thru the math!