tape foot measurement of the girth of the calf, to ensure the shaft of the boot fits the leg
Measurement can be taken at specific heights up from the heel, such as 5”, 7”, and so on.
Measurements can also be taken at particular anatomical points, such as at whatever point the leg is widest. The height up from the heel is often noted along with the girth measurement.
Calf girth measurements help ensure that boot shafts don’t constrict the legs. For laced boots, they also help to achieve the intended spacing between facings.