How to judge the fit of safety shoes? Here is an introduction about the fit of safety shoes: Because there are many types of human feet-fat feet and thin feet, it is very important to formulate suitable lasts for these foot types, but the size of these lasts is also generated according to the grading system. In the British safety shoe size and the American safety shoe size system, the ankle length of each shoe size in the small size segment (that is, the foot of a child under 169 mm) is increased by 3/16 inches (4.76 mm) in the large size segment. Increase by 1/4 inch (6.35 mm). When the safety shoe size is lowered, the ankle length is also reduced by the same data. With the geometric grading system, the last length difference of each yard is 3%. With the Paris scale system, the ankle length of each safety shoe size changes to 5 mm.