A fancy machine called a digital contact sensor measures the ‘stack height’, or the total thickness of the sole from your foot to the ground, in both the heel and the forefoot. The ‘drop’ is the difference between the heel and the forefoot measurements, or how much your toes drop below your heel. The least amount of drop in this guide is 0mm for both men and women (Altra King 1.5, Vivobarefoot Primus Swimrun). The greatest amount of drop is 14.4mm for men and 12.9mm for women (Reebok Harmony Road 2).
0mm LEAST 14.4mm MOST