Tall boots are an investment, and therefore need to be fitted correctly to last. Start by sitting in a chair foot flat on the ground barefoot; measure from the back of your heel to the back of your knee. Add approx 1 ¼ to 1 ½ inches for drop (as the leather breaks in the boots will drop). Next measure the widest part of your calf over your riding clothes. Compare these measurements and your foot size to the mfg sizing chart.