Shoe sizes use different standards by country/region and are not unified. Here's an explanation of major standards.
Japanese Shoe Sizes (JIS Standard)
Japan uses centimeters (cm) representing actual foot length. Increments by 0.5cm, with typical men's sizes 24.5cm-28cm and women's 22cm-25cm.
US Shoe Sizes
US uses inch-based unique values. Same foot length has different numbers for men and women - men's 8 = women's 9.5. Increments by 0.5.
UK Shoe Sizes
UK is also inch-based but uses different baseline than US. Generally 0.5-1 size smaller than US sizes.
European Shoe Sizes (EU)
Europe uses "Paris Points" unit, approximately 2/3cm (6.67mm) per unit. Same numbers for men and women, ranging 35-48. Many brands lack half sizes.
Chinese Shoe Sizes (CN)
China uses millimeters (mm). Japan 25cm = China 250, essentially Japan size × 10.
Kids' Shoe Sizes
Kids' sizes change complexly with growth stages. US uses "C" (Child) and "Y" (Youth) notations, with size systems changing by age. Typically choose 0.5-1cm larger considering growth.
Brand Variations
Actual measurements vary by brand even with same size notation. Nike (runs small), Adidas (standard), New Balance (runs large) - each brand has characteristics.
Size Conversion Notes
This tool is based on general standard size charts, but actual products may vary by brand/model. Always check product page size charts before purchasing.