Free Shoe Size Converter — US, EU, UK, Japan

US sizes use a numeric scale starting around size 6 for men and 5 for women, increasing in half-size steps. EU sizes use a single unified scale based on the Paris point (2/3 cm per size), typically running 39–46 for men and 35–42 for women. A men's US 10 is roughly an EU 43. The systems use different starting points and step sizes, so direct math doesn't work — use a conversion table.

Yes, in the US and UK. US men's sizing runs about 1.5 sizes larger than women's in the same shoe — a women's 9 ≈ a men's 7.5. The EU system uses one unified scale for both. Japanese sizes also use one scale (foot length in cm) with no gender split.

Stand on a piece of paper with weight evenly distributed (your foot is largest when bearing weight). Mark the back of your heel and the tip of your longest toe — for most people that's the big toe, but some have a longer second toe. Measure heel-to-toe in millimeters. Convert to cm for JP sizing or look up the equivalent in US/EU/UK tables.

Yes, especially for athletic shoes. US width codes (narrow to wide): AA/B (women's narrow/standard), B/D (men's standard), 2E/4E (men's wide/extra wide). EU sizing typically does not encode width — narrow and wide are sold as separate models or simply unavailable. Many running brands now publish width on the product page.

Manufacturing tolerances, last shape (the foot-shaped form a shoe is built around), and intentional fit choices. Italian brands (Gucci, Prada) tend to run small. American athletic brands (Nike, Adidas) run true to size for athletic, slightly small for casual. Doc Martens famously run a full size large — sizing down is standard. When ordering online for the first time, read recent fit reviews specific to that model.

Historical accident plus inconsistent standardization. Each system evolved independently. US sizes are based on a 19th-century English shoemaker's barleycorn unit (1/3 inch). UK sizes are similar but offset slightly. EU sizes are based on Paris point (2/3 cm), measured in different ways by different brands. Japanese sizes use direct cm measurement, the most rational of the systems. There's no international standard force people to align — each brand and country uses whatever system fits their tradition. The result is a mess for international shoppers and tourists.

Read brand-specific reviews. Some brands consistently run small (Nike, Vans, Converse), some run large (Brooks, Hoka), some run true to size (Adidas, New Balance most models). 'Runs small' = order 0.5-1 size up from your usual. 'Runs true' = order your usual. 'Runs large' = order 0.5 size down. Beyond brand: foot shape matters more than nominal size. Wider feet may need different brands (New Balance, Allen Edmonds, Brooks for casual; Topo for running). Narrow feet may prefer European brands. The single best information source: foot-measured reviews on Reddit (r/Sneakers, r/RunningShoes) for specific shoe models.

Yes, by about 0.5-1 size over adult lifetime. Foot length stabilizes by late teens but width often increases with age (gravity, weight changes, pregnancy in women). Plantar fascia and arch can flatten over decades, lengthening the foot slightly. The biggest changes: pregnancy can permanently increase foot size by 0.5 size; significant weight gain or loss affects foot dimensions; foot trauma or surgery can change size. Most people end up wearing a half-size larger in their 40s-50s than they did in their 20s. Re-measure your foot every 5-10 years; don't assume you're 'still a size 9' from college.

Foot expansion during exercise. Feet swell 5-15% in volume during running due to blood pumping and impact forces. Running shoes are typically sized 0.5 size larger than dress shoes to accommodate this swelling without toe-jamming. Other factors: running shoe brands typically run smaller than dress shoe brands (Brooks runs slightly larger than this trend); thicker sock thickness adds room needs; downhill running benefits from extra room to prevent black toenails. Standard advice: try running shoes on after a run or workout when feet are slightly swollen; size up 0.5 from dress shoe size.

Width designations in US sizing. Men's standard width is D; wide is E or EE; extra wide is EEE or 4E. Narrow is C or B. Women's standard is B; wide is D; extra wide is EE. UK uses similar letter system. EU sizes generally don't indicate width — width assumed standard with limited variety. Brand-specific width variety: New Balance offers wide options in nearly every model (a major reason for their popularity); Brooks running shoes available in wide; Allen Edmonds dress shoes offer multiple widths. Most fashion-oriented brands (Nike, Adidas) don't offer width variations — accepting their fit or moving to a different brand are the options.