People's left and right feet are basically symmetrical, but there must be subtle differences, so you should choose a bigger one when measuring.
international standard
The Mondopoint shoe size system recommended by ISO standard ISO 9407 is based on the width and average length of feet, with millimeters as the basic unit.
Extended data:
Chinese mainland's old code and European code (French code, EU code) are essentially different and cannot be confused or used interchangeably. China and Hongkong have always followed the European size system, taking the European code as the standard unit. Japan and Chinese mainland have the same new shoe size, using the standard Mondo 5 mm decimal system.
Shoe sizes in the United States and Canada measure the length of last in inches:
Men's shoe size = 3* last length -22
Women's shoe size (normal) = 3* last length -20.5
In addition, there is a relatively rare size of women's shoes, which was put forward by the American Footwear Association:
FIA = 3 * final length -2 1
The shoe size of boys and girls is the calculation method of men's shoe size+12.33.
Baidu encyclopedia-shoe size