Foot Morphology and Fitting of the Shoe to the Foot
In the Japanese shoe size system, shoe size is determined by length and ball girth. The shoe size indicates the size of the foot that fits the shoe, not the size of shoe itself. Human foot length and foot circumference correspond to the length and ball girth of the shoe respectively.
Length is indicated in cm. Since foot circumference could vary widely ,even when the foot length is the same, there are shoes of the same length with different ball girths. A shoe with average circumference is called "E". It becomes "EE", "EEE", "EEEE", with increasing ball girth, and becomes "D", "C", "B", "A" with decreasing ball girth.
Shoe length increments by 0.5 cm, and ball girth by 3 mm. In the Japan Industrial Standard (JIS) for shoes, the sizes range from 20A to 30G for adult males, from 19.5A to 27EEEE for adult females, and from 10.5B to 26G for children's shoes.
A shoe is manufactured on a last, so last size and shape determines the size and shape of the shoe.
For a proper fit, length and ball girth of the shoe must match to the length and circumference of the foot. The foot shape may vary even when the foot length is the same. Any shape mismatch causes disuncomfort. Through research into the size and shape variations of Japanese feet, we are developing a method of shoe design that takes shape characteristics into consideration.