Shoe Size Conversion Explained: US, UK, EU, cm and Mondopoint

Shoe size conversion works by turning each size back into a length. UK and US sizes step by a barleycorn, a third of an inch (8.47 mm); EU sizes step by a Paris point, two-thirds of a centimeter (6.67 mm); and Mondopoint is simply your foot length in millimeters. On a standard chart, a men’s US 9 is a UK 8 and an EU 42.

Because the systems use different units and different starting points, their numbers never line up neatly, and charts have to round. This guide explains how each system is built, gives a reference chart, shows why two brands can disagree by half a size or more, and covers how to measure your feet so you can convert with confidence. For any size, the shoe size converter does the conversion in both directions.

Sizes are lengths of the last, not your foot

Most systems measure the last, the foot-shaped form a shoe is built around, rather than the foot itself. The last has to be longer than your foot to leave room for your toes. Our charts allow two-thirds of an inch, about 1.7 cm, of toe room, which matches the common US foot-measuring scale. Mondopoint is the main exception: it labels a shoe by the foot it is meant to fit.

Shoe size conversion: how each system works

The barleycorn. An English measure traditionally dated to 1324, under Edward II, set the inch at three barleycorns laid end to end. Britannica’s history of the shoe describes the longest normal foot, 39 barleycorns or 13 inches, being called size 13, with smaller sizes stepping down a third of an inch at a time. Modern UK sizes still count up one barleycorn per size.

The Paris point. Continental European sizes count the last in Paris points of two-thirds of a centimeter, so an EU number is one and a half times the last length in centimeters. A 28 cm last is EU 42.

Mondopoint. The international standard ISO 9407 sets out a system for marking footwear by measurements of the foot it’s intended to fit, in millimeters. You’ll see it most often on ski and snowboard boots. ISO publishes other standards that turn up in everyday life too, including the week-numbering rules in our ISO week numbers guide.

Reference chart: adult sizes

Built from the definitions above, with EU rounded to the nearest half size and foot length rounded to the nearest millimeter:

Notice that EU steps by 1 or 1.5 for each full UK size. A barleycorn (8.47 mm) is about 1.27 Paris points (6.67 mm), so the two scales only line up every few sizes. As a rule of thumb from this chart, UK is roughly EU minus 33 for EU 35 to 40, and EU minus 34 from EU 40 to 45.5. Ready-made tables: EU to UK sizes and US to EU sizes.

Converting by hand

• UK to EU: add 25 to the UK size, divide by 3 to get the last in inches, multiply by 2.54 for centimeters, then by 1.5. UK 8: 33 ÷ 3 = 11 in = 27.94 cm, × 1.5 = 41.91, so EU 42.
• EU to foot length: divide by 1.5 for the last in centimeters, then subtract about 1.7 cm of toe room. EU 42: 28.0 − 1.7 = 26.3 cm. The chart shows 26.2 cm because the EU number itself was rounded.
• Men’s to women’s US: add 1.5. A men’s 9 is a women’s 10.5. See the men’s to women’s size chart.
• Mondopoint to US men’s: divide by 25.4 for inches, multiply by 3 and subtract 22. Mondopoint 270: 10.63 × 3 − 22 = 9.89, so about a US 10.

Why brands don’t match the chart

A conversion chart tells you how the systems relate in theory. A real shoe can still fit differently, for reasons the chart can’t capture:

• Different lasts. Each brand shapes its lasts differently: pointed or round toes, high or low insteps, narrow or wide heels. Two shoes with the same size printed inside can have different inside lengths.
• Different charts. Some brands use their own conversion tables, and US–UK offsets vary by brand and by men’s or women’s lines. Always check the brand’s own chart if it has one.
• Rounding. Because EU and UK steps don’t divide into each other, every chart rounds somewhere, and two charts may round the same size in different directions.
• Width. Length-only systems say nothing about width. A shoe that is the right length can still feel small if it’s too narrow.
• Type of shoe. Running shoes, boots and ski boots are often fitted with more or less room than street shoes.

How to measure your feet

1. Stand on a sheet of paper with your heel against a wall and your weight on that foot. ISO 9407’s definition of foot length is taken standing, with body weight spread evenly over both feet.
2. Mark the tip of your longest toe, which isn’t always the big toe, keeping the pen upright.
3. Measure from the wall to the mark in centimeters or millimeters.
4. Repeat for the other foot and use the longer measurement.
5. Wear the socks you plan to wear with the shoes.

Enter that bare-foot length as “foot length” in the converter, not as a shoe size, because the shoe has to be longer than your foot. Don’t measure an old insole and treat it as your foot length. Children’s sizes use separate scales that restart at zero; the kids’ shoe size chart covers toddler, little kid and big kid sizes.

Frequently asked questions

How do you convert US shoe size to EU?

Subtract 1 from a men’s US size to get the UK size, then convert UK to EU. A men’s US 9 is UK 8, which is EU 42 on a standard chart. For women’s sizes, subtract 2.5 to get UK.

Is a UK size the same for men and women?

Yes. UK and EU sizes use one scale for everyone. Only US sizes have separate men’s and women’s numbers, 1.5 sizes apart.

What is a barleycorn in shoe sizes?

An old English unit of a third of an inch, about 8.47 mm. UK and US shoe sizes go up by one barleycorn per full size, and half sizes by a sixth of an inch.

What is Mondopoint?

A sizing system from ISO 9407 that labels footwear by the length of the foot it fits, in millimeters. It’s common on ski boots: a Mondopoint 270 boot fits a foot about 270 mm long.

Why does my EU size change between brands?

Brands shape their lasts differently and round their charts in different ways, so the same EU number can fit up to half a size or more apart. Check the brand’s own chart and, if you can, measure your foot.