US vs EU shoe size: why every conversion table disagrees

TL;DR.EU shoe sizes are in Paris points (~6.67 mm increments) and US sizes are in barleycorns (~8.47 mm half-size increments), so the systems don’t line up cleanly — and neither measures the foot directly. The only reliable conversion is to measure your foot in millimetres and consult the specific brand’s chart.

Shoe sizing across regions is a mess. EU sizes use the Paris point (about ⅔ cm). US sizes use the barleycorn (⅓ inch). The UK uses a similar barleycorn system offset from the US one. And none of these systems measure the foot — they measure the last, the wooden form the shoe is built around, which varies between manufacturers. That’s why a 9 US in Nike doesn’t fit the same as a 9 US in Adidas.

The actual definitions

Why the brand matters more than the conversion table

Last shape varies between brands. Nike’s lasts are relatively narrow; New Balance offers width grades; Italian dress shoes (Allen Edmonds, Salvatore Ferragamo) often run narrow in standard widths. Two shoes labelled “9 US” from different brands can differ by 5-10 mm in actual interior length, plus differences in toe-box volume, instep, and heel cup.

For online ordering, the most reliable workflow:

1. Measure your foot in mm (heel to longest toe).
2. Find the brand’s own size chart that maps EU/US to that mm length.
3. Use that specific brand’s mapping, not a generic conversion.

The Mondopoint shortcut

Mondopoint (ISO 9407) is the only system that measures the actual foot in millimetres. Military boots, skiing, and skating use it. Athletic brands print Mondopoint on the box next to the EU/US size. If you know your foot length in mm, you can look up the Mondopoint number and bypass the conversion uncertainty entirely.

Typical adult Mondopoint values: 240 mm (US men’s 7), 260 mm (US 9), 280 mm (US 11), 300 mm (US 13).

A practical conversion table

The numbers below are accurate for most athletic brands. Dress shoes typically run half a size larger than these suggest.

The men’s/women’s offset

US men’s sizes are 1.5 numbers lower than US women’s for the same physical shoe. A US men’s 8 is a US women’s 9.5. EU and Mondopoint don’t encode this offset — they’re unisex. UK uses one numbering across genders. The split is purely a US retailing convention.

Calculator

Convert any direction with our shoe size converter, which uses the standard barleycorn/Paris-point math (not a brand-specific chart).

Numeric facts

• 1 Paris point = 2⁄3 cm = 6.667 mm; one full EU size advances the last by exactly that distance.
• 1 barleycorn = 1⁄3 inch = 8.467 mm; one full US/UK size advances the last by that distance, and one half-size by 4.233 mm.
• EU↔US gap per step: a full EU size moves the last 6.67 mm; a full US size moves it 8.47 mm — so the two scales drift by ~1.8 mm per step, which is why “round” cross-conversions land on half sizes.
• Mondopoint resolution: ISO 9407 specifies 5 mm increments (consumer) or 7.5 mm (military); foot length is stated to the nearest 5 mm.
• Last vs foot allowance: the inside length of a shoe (“last length”) is typically 1.5-2 sizes larger than the wearer’s foot to allow toe wiggle room and forward slide during gait.
• Width grades: US width letters (B, D, EE, EEEE) each add ~3.2 mm at the ball circumference; EU width letters (F, G, H) each add ~5 mm.
• Daily foot-size swing: adult feet swell 4-8% in volume over a day; measure in the late afternoon for the most accurate fit reading.

Decision matrix

Sources

• ISO 9407:2019 — Footwear sizing, Mondopoint system — iso.org.
• Brannock Device Company — original 1927 US foot-measuring spec — brannock.com.