Choose by centimeters (CM) If you are buying this model for the first time, we suggest you choose the size based on the length (in centimeters) of your foot. How to do? Wear the type of socks you usually use, standing on a hard surface with a sheet of white paper under your feet distributing the weight evenly. Measure from the edge of the paper under the heel to the longest part of the foot, which may or may not be the big toe, using a ruler to measure the marked length in centimeters. Identify the length and compare it with the references you find in this table to choose the right number to buy.