US vs EU Shoe Sizes Explained

Two systems, two rulers

US shoe sizing descends from the English Barleycorn system, where a full size equals one-third of an inch (about 8.47 mm) and a half size is one-sixth of an inch. It is a length scale, but it starts from an offset that varies by gender and age. European sizing uses the Paris Point, where a full size equals two-thirds of a centimeter (6.67 mm). It measures the length of the shoe last — not the foot — in a linear, half-size-free scale.

That's why the increments feel different. Going up one US size adds 8.47 mm of length; going up one EU size adds only 6.67 mm. Between EU 42 and EU 44 there is only one intermediate size (43), while between US 9 and US 11 there are three (9.5, 10, 10.5).

The men's conversion chart

The women's conversion chart

US women's sizes sit 1.5 sizes higher than US men's for the same last, but EU sizing does not distinguish gender at all — the number describes shoe length. So a US women's 9 shares an EU value with a US men's 7.5.

Where the conversion breaks down

Half sizes are the main friction. EU sizing traditionally has no half sizes — a US 9.5 doesn't have a clean EU counterpart, so brands round differently. Nike calls that shoe a 43. Adidas calls it a 42.5 (yes, they use half sizes in EU labeling). New Balance often lists both 42.5 and 43 as options for the same US 9.5, distinguished by width.

The second friction is the last shape. Two brands making a shoe for a 27.0 cm foot can build very different fits — narrow versus wide, low volume versus high volume, generous toe box versus tapered. A conversion chart tells you which number to look at; it can't tell you whether that number will fit.

Practical rules

• Measure your feet in centimeters, standing, late in the day.
• Convert with the chart above as a starting point.
• Read the brand's own fit notes — 'runs half a size large' is real.
• If two sizes are borderline, order the larger one for closed shoes and the smaller one for sandals.