a tape foot and last measurement around the bottom, back point of heel and the top of the instep
contrast the long heel
Short heel measurement is particularly important for slip-on shoes, such as western boots, that rely on close fitting vamps without laces to hold the foot in place, but must be wide enough at the “pass” to allow the foot to enter.
Short heel measurements change as the ankle bends. Measurements with pointed toe read shorter than with the ankle in walking position or bent upward. https://youtu.be/lr4F0PxQk4Q