In two similar geometric figures, the ratio of their corresponding sides is called the scale factor. To find the scale factor, locate two corresponding sides, one on each figure. Write the ratio of one length to the other to find the scale factor from one figure to the other. In this example, the scale factor from the blue figure to the red figure is 1.6 : 3.2, or 1 : 2. This means that for one unit of length on the blue figure, there are two units of length on the red figure. The scale factor from the red figure to the blue figure is 3.2 : 1.6, or 2 : 1.