Your Japanese shoe size is simply the length of your foot in centimeters. The best way to determine your Japanese shoe size is to stand up straight on a piece of paper and have a friend (or loved one) make pencil marks at the front-most and back-most points of your foot while holding the pencil perfectly vertical. Measure the distance between the two lines in centimeters. That's your Japanese shoe size! Alternatively, you can consult the approximate conversions below. Because the shoes are form-fitting, correct sizing is crucial for maximum comfort.