Shoe Size Conversion Calculator

This converter works from one input, foot length, and pushes it through six national conventions that were never designed to agree. The US scale is built on the barleycorn of one third of an inch per full size, expressed here as US men = 3 x length in inches - 22, with women's numbers offset about 1.5 above men's for the same foot. The European scale uses the Paris Point of 6.667 mm, applied to the last rather than the foot, so EU is approximately (length in cm + 1.5) x 1.5 with no gender split. Japan uses Mondopoint, the foot length in centimeters itself, and Korea the same figure in millimeters, making both directly interpretable. Brazil uses its own linear scale near (length in cm - 8.2) / 0.65. Width is the dimension most conversions drop. US width letters run from AAA through D to EEEE, each letter step being roughly a quarter inch, about 6.35 mm, of ball circumference; D is the men's standard and B the women's, which is why the same letter means different things by gender. Foot width is commonly near 38 to 39 percent of foot length. Every output here is nominal: lasts differ between manufacturers by several millimeters at the same printed size, feet swell up to half a size over a day, and athletic lasts usually run longer than dress lasts, so measure in the evening and compare against insole length.

The English-speaking scales rest on the barleycorn, one third of an inch, a unit that shoemakers used as a size increment long before any government standard existed and which is traditionally linked to a medieval English definition of the inch as three barleycorns laid end to end. Britain fixed a children's scale beginning near four inches and continued the same increments into adult sizes; the American scale adopted the same step but a slightly different origin, which is the mechanical reason a US men's number sits about half a size above the UK number for the same foot. France developed the Paris Point in the nineteenth century, and it spread across continental Europe as a single ungendered scale. Measurement, as opposed to labelling, was transformed in the United States by Charles F. Brannock of Syracuse, New York, who worked in his family's shoe store and patented a sliding device in the late 1920s that read heel-to-toe length, arch length and width simultaneously. The Brannock Device Company standardised American fitting practice around it, and the device remains in use in shoe shops today. The international answer came later with Mondopoint, adopted in ISO 9407, which designates footwear by mean foot length and width in millimeters and is used in military and safety footwear procurement precisely because it is a measurement rather than a legacy numbering.