Joli Sayasane gives you a lesson on how much extra fabric and where to add it. You will learn that you need to add ½ to the height and width of squares and rectangles, 7/8 to the short side of half square triangles, 1 ¼ to the long side of quarter square triangle, and either multiply or divide by 1.414 for a triangle depending on the side. Try to memorize these cut sizes to easily give you finish sizes that you want.