Shoe Size Converter

Shoe Size Converter

Convert between US, UK, EU, and CM/JP shoe sizing systems. Each uses different scales, and conversions differ by gender.¹

Men’s Sizes

Women’s Sizes

How Shoe Sizing Systems Work

There's no universal shoe sizing standard, which is why converting between systems is so confusing. The four major systems: US (based on barleycorns, ⅓ inch increments, different scales for men/women/children), UK (similar to US but offset by ~0.5-1 size), EU (Paris points, ⅔ cm increments, unisex), and CM/Mondopoint (foot length in centimeters, used in Japan/Korea and military footwear). A US men's 10 = UK 9 = EU 43 = 28 cm foot length.

Why Sizes Vary Between Brands

Here's something most people don't realize: shoe sizes are surprisingly inconsistent across manufacturers. A size 10 from Nike, New Balance, and Allen Edmonds may all fit differently because each brand uses its own proprietary lasts (the 3D foot form around which shoes are built). Width also varies — a "D" width (standard men's) from one brand may be narrower than another's. Studies have found that actual interior measurements of same-size shoes can differ by up to 1 cm between brands. That's why trying shoes on (or buying from retailers with free returns) is still essential even when you know your measured size.

Measuring Your Feet Correctly

Measure both feet — most people have one foot slightly larger than the other (typically the dominant side, by half a size to a full size). Always measure in the afternoon or evening when feet are at their largest (feet swell 5-8% throughout the day). Stand on the measuring device with full weight — seated measurements are shorter. Measure from heel to longest toe (which may be the second toe, not the big toe, in about 20% of people). Add a thumb's width (~½ inch) between your longest toe and the shoe end for walking shoes; less for dress shoes.

Children's Shoe Sizing

Children's sizing gets even trickier. U.S. children's sizes run 0-13, then jump to men's/women's sizing (children's 13 ≈ men's 1). Kids' feet grow approximately one full size every 3-4 months until age 3, then about one size per year until adolescence. Fitting shoes too tight can cause long-term foot problems; fitting too loose causes blisters and tripping. The American Academy of Pediatrics recommends checking fit every 2-3 months and replacing shoes when there's less than a finger's width of room at the toe.

Width Sizing Explained

Width designations use letter codes: Men's: B (narrow), D (standard), E/EE (wide), EEE/EEEE (extra wide). Women's: AA (narrow), B (standard), D (wide), EE (extra wide). About 25% of the population has feet significantly wider or narrower than standard width. Wide-width shoes are harder to find in stores but widely available online from brands like New Balance, Brooks, ASICS, and specialized retailers. Proper width fitting prevents bunions, corns, and neuromas — conditions caused by chronic compression of the forefoot.

International Shoe Size Systems Explained

No universal shoe sizing standard exists, and the differences between systems are not simple linear conversions. The US/Canada system uses different scales for men, women, and children — a women's size 9 is roughly a men's 7.5 in the US. The UK system runs about 0.5-1 size smaller than US men's (US 10 ≈ UK 9.5) and about 2 sizes smaller than US women's (US women's 8 ≈ UK 5.5). The European (EU/Continental) system measures foot length in Paris points (2/3 centimeter each): EU 42 = 42 × 2/3 cm = 28 cm foot length, roughly US men's 8.5-9. Japanese sizing (cm/Mondopoint) directly measures foot length in centimeters: a 27 cm foot wears a JP 27, which equals approximately US men's 9, EU 42, UK 8.5. This direct measurement makes Japanese sizing the most logical system, but vanity sizing, last shape variations, and brand inconsistencies mean even centimeter-based sizes are approximate.

Why Sizes Vary Between Brands

A size 10 in Nike can fit differently from a size 10 in Adidas, New Balance, or Red Wing — a phenomenon called "size inflation" or vanity sizing in footwear. Athletic shoe brands tend to run slightly large (a Nike 10 might measure like a true 10.25) because consumers associate larger sizes with comfort and are more likely to purchase shoes that feel roomy during a quick try-on. Dress shoe brands, particularly European ones, tend to run true or slightly small. Work boot brands like Red Wing and Thorogood typically size true to Brannock device measurements. The Brannock device — the metal foot-measuring tool found in shoe stores — measures three dimensions: overall length (heel to longest toe), arch length (heel to ball of foot), and width. The larger of the two length measurements determines your Brannock size. Getting professionally measured every 2-3 years is recommended because feet change shape over time — weight gain, pregnancy, aging, and injury can alter foot dimensions by a full size or more.

Width Sizing: The Overlooked Dimension

Most shoe shoppers focus exclusively on length, but width is equally important for comfort and foot health. Standard US width designations run from AAA (narrowest) through D (standard men's / wide women's) to EEE or 4E (extra wide). A men's size 10D has a forefoot width of approximately 4 inches, while a 10 2E measures about 4.25 inches and a 10 4E about 4.5 inches. Half an inch of width difference transforms a painful shoe into a comfortable one. Signs you need a wider shoe: the leather bulges over the sides of the sole, you have pain at the ball of the foot, or your pinky toe presses against the shoe's edge. About 25% of people have feet significantly wider or narrower than standard, yet most retail stores stock only D (men's) and B (women's) widths. Brands offering extensive width ranges include New Balance (2A through 6E), Brooks, and Allen Edmonds. Ordering the wrong width online leads to approximately 30% of shoe returns — measuring your foot width at home with a ruler across the widest part of the ball helps avoid this expensive trial-and-error.

Measuring Your Feet at Home

Getting an accurate measurement at home is simpler than you'd think, but technique matters. Stand on a piece of paper (feet expand under weight versus sitting), trace around each foot with a pencil held vertically, then measure the longest distance from heel to toe and the widest distance across the ball. Measure both feet — roughly 60% of people have one foot measurably larger than the other, and you should size for the larger foot. Measure in the evening when feet are largest (they swell 5-8% during the day from standing and walking). Add 10-15 mm to your traced foot length for "thumb's width" of toe room — your longest toe should not touch the front of the shoe when standing. For athletic shoes, add slightly more (15-20 mm) because feet swell during exercise. For children, feet grow approximately one full EU size (6.67 mm) every 3-4 months up to age 3, then about one size every 4-6 months until age 6. Shoes should be replaced when there's less than 10 mm of space ahead of the longest toe — cramped shoes in growing children can cause permanent structural issues including hammer toes and bunions.

Shoe Size and Health Implications

Wearing the wrong shoe size doesn't just cause discomfort — it can lead to real musculoskeletal problems. Shoes too narrow cause bunions (hallux valgus), hammertoes, neuromas (nerve inflammation between metatarsals), and corns. Shoes too short jam toes on each step, leading to blackened toenails (subungual hematoma) — a common complaint among runners who size too tightly. Shoes too large cause blisters from sliding and altered gait mechanics that strain ankles and knees. High heels above 2 inches shift body weight forward onto the metatarsal heads, increasing forefoot pressure by 75% at 3-inch heels and creating shortened Achilles tendons with chronic use. Podiatrists estimate that 70-80% of adults are wearing shoes that don't actually fit — partly because most people haven't measured their feet since their last growth spurt and assume their size hasn't changed, when adult feet actually keep changing shape throughout life.

How to Use This Calculator

1. Select gender — Men, women, or children.
2. Enter size — In any system.
3. See all — Conversions displayed.

Tips and Best Practices

See also: Length · Weight · Temperature