1. The unit of measurement for the above data is millimeters. 2. Step on a piece of white paper with your foot, mark the front and back positions with a pen, and the distance between the two points is the correct foot length. 3. There is a slight difference in the size of the left and right feet, and the data of the larger foot should be taken as the standard. 4. If the instep is high and the foot shape is wide and fat, it is recommended to choose a larger size; if the instep is flat and the foot shape is slender, it is recommended to choose a smaller size. 5. The measured size should be roughly the same as the size you usually wear. If there is a large deviation, it means that the measurement method is incorrect or the data is not accurate enough.