One Foot, Four Numbering Systems

Shoe sizes are four different rulers measuring the same foot. The US scale is linear in inches (US men's = 3 × inches − 23, women's 1.5 sizes higher), the UK scale runs a half size below US men's, EU sizes follow foot length (≈ cm × 1.5 + 2), and Japan's mondopoint system simply uses the foot length in centimeters. The converter shows all four for any foot.

Centimeters Are the Common Denominator

Every size system was built around foot length, which is why centimeters — or mondopoint — is the only measurement that converts cleanly across brands and regions. When ordering internationally, compare the cm length in the product listing against your own measurement; the labeled size is a translation, and translations vary.

Brands Are the Wildcard

Lasts differ: a running shoe fits differently than a dress shoe in the same size, and brands drift a half size in either direction. The Advanced Options fit adjustment shifts the result for brands that run small or large, and the honest rule still applies — if a brand's chart lists foot length, use it over the size number.