Shoe sizing is surprisingly inconsistent across the globe, with four major systems — US, European (EU), British (UK), and Japanese (JP/CM) — each using different measurement bases and increments. The US system, based on the Brannock Device invented in 1927, starts at size 1 for a foot measuring approximately 7.33 inches and increases by one-third of an inch per size. European sizing uses the Paris Point system, where each size equals 6.67 millimeters (two-thirds of a centimeter), starting from size 15 for infants. The UK system is similar to the US but offset by approximately 0.5 to 1 size for men and 2 sizes for women. Japan uses the simplest system — direct foot length in centimeters, so a size 27 means a 27 cm foot. To complicate matters further, men's and women's sizes differ within the same country (a US women's 9 equals a US men's 7.5), and brands like Nike, Adidas, and New Balance each have slight variations within the same system. With global e-commerce making international shoe purchases routine, accurate size conversion prevents costly returns — online shoe return rates average 20-30%, with incorrect sizing cited as the primary reason.
Understanding international shoe size systems
There are four major shoe sizing systems used worldwide. The US system (Brannock scale) is used in the United States and Canada, with separate scales for men, women, and children. The EU system (French Paris point) is used across Europe and is unisex — a EU 42 is the same length for men and women. The UK system is used in Britain, Ireland, Australia, and New Zealand, and is similar to the US system but offset by about 0.5 to 1 size for men. The JP system, used in Japan and much of East Asia, is the simplest — it equals the foot length in centimeters. All systems ultimately map to foot length, making centimeters the universal translation layer.
Why shoe sizes vary between brands
Even within the same sizing system, a size 10 from Nike may feel different from a size 10 from Adidas. This is called vanity sizing or last variation — each brand uses slightly different shoe lasts (foot-shaped molds) and may round sizes differently. The best way to ensure a good fit when buying from an unfamiliar brand is to measure your foot length in centimeters and compare it to the brand's specific size chart. Our converter provides the standard industry conversions, which work as a reliable starting point for most major brands.