International Shoe Size Converter

US men's and women's shoe sizes use separate scales that are offset by approximately 1.5 sizes — a US women's 9 equals approximately a US men's 7.5. This historical distinction developed because the footwear industry traditionally manufactured on different lasts for men and women, with women's lasts being narrower and shorter-toed for the same size number. The separate scales persist today even though modern shoe design often blurs traditional gender distinctions. When men wear women's shoes or vice versa (as in some athletic shoe categories), they typically need to adjust by 1.5 sizes.

Shoe size variation between brands is caused by differences in the 'last' — the foot-shaped form over which the shoe is constructed. Each brand designs their own lasts, which vary in length, width, toe box shape, arch profile, and heel cup depth. A Nike size 10 may have a different internal volume than an Adidas size 10 even though both claim to be the same size. This is why it is impossible to guarantee fit by size alone — especially for online purchases. Always read brand-specific fit reviews and check return policies when buying footwear online.

The most reliable method is to measure your foot length in centimeters at the end of the day (feet swell slightly throughout the day). Stand on a piece of paper, trace your foot, and measure from heel to the tip of your longest toe. Repeat for both feet — most people have one foot slightly larger than the other; always size for the larger foot. Convert your centimeter measurement to the target sizing system using a standard chart, then reference the specific brand's fit guide for final confirmation. For running shoes, add 0.5–1 cm to your measured foot length for proper running room.

Japanese shoe sizes are simply the foot length in centimeters, rounded to the nearest 0.5 cm. A JP size 25.0 means the shoe fits a 25.0 cm foot length. This is the most intuitive system of all shoe sizing conventions. Japanese sizes are also sometimes written with an E suffix (25.0E, 25.0EE) to indicate width — E is standard width, EE is wide. When shopping Japanese brands internationally, convert your foot length in cm directly to the JP size. This system is also used in some Korean and other East Asian shoe sizing conventions.

Half sizes represent a 4.23 mm (1/6 inch) increment in foot length — one-half of a full barleycorn size. When you fall between sizes, general guidance is to size up for running shoes and athletic footwear (to allow room for foot expansion during exercise and to prevent toe impact on the shoe front), and to use judgment for dress shoes based on the shoe's construction and your foot width. Narrow feet in standard lasts often fit better in a half size down; wide feet may prefer the half size up. Insoles can fine-tune fit within half a size.

European shoe sizes are often 30+ numbers higher than equivalent US sizes (EU 40 ≈ US Women's 9 / Men's 7.5), which can be initially confusing. The EU system is based on Paris points — each point equals 2/3 of a centimeter. The EU size number equals the length of the last in Paris points. So EU 40 means the last is 40 × 2/3 cm = 26.7 cm long, which corresponds to a foot of approximately 25.7–26.0 cm (shoes are slightly longer than the foot). This system is more mathematically consistent than the US/UK systems but requires a conversion lookup for North American shoppers.

Children's shoe sizes run from approximately UK 0 (infant, ~9 cm) up to UK 13 (child, ~22 cm), then transition to adult sizing starting at UK 1 (adult). In EU terms, children's sizes run from about EU 16 through EU 32–33, where adult sizes begin. In US terms, children's sizes reach up to US 6 (toddler/child scale), after which adult sizing begins at US 1. The transition point is typically around ages 11–13 for girls and 12–14 for boys, depending on foot growth. At the transition, children are measured and switched to adult sizing charts — the adult sizes are not directly continued from children's sizes.

Yes, foot width significantly affects international sizing decisions. US sizing explicitly acknowledges width with letter codes (AA/narrow through 4E/extra-wide). Most European brands do not use explicit width codes and assume a standard width; they may offer only one or two widths in some styles. If you have wide feet and are buying European shoes, you may need to go up 0.5–1 EU size to accommodate your foot width. Conversely, narrow-footed people may need to go down a half size in some European brands. For athletic footwear, brands like New Balance and Brooks offer explicit width options that translate internationally.