Shoe Size Converter

Three scales, three different ideas of a foot

The numbers stamped inside a shoe are not measurements of your foot. They are measurements of the last — the plastic form the shoe was built around — expressed in three unrelated units that were invented centuries apart. That is the whole reason conversion is annoying.

The UK scale counts barleycorns: one third of an inch per full size, half sizes at a sixth of an inch, counted up from a fixed zero point set for children's feet. The US adopted the same step but shifted the starting number, which is why a US men's size runs one number above the UK equivalent and a US women's size runs about two above. The EU scale counts Paris points, each two thirds of a centimetre, with no half sizes in the original system — the 41.5 you see on a box is a modern retail invention. Mondopoint, the cm scale, is the only one that describes your actual foot: it is the length of the foot in millimetres or centimetres, which is why ski boots, military boots and most Japanese and Korean brands use it.

This converter treats the cm column as the truth. Whatever you enter is translated into a foot length first, then read back out in every other system, which keeps the three answers internally consistent instead of chaining approximations.

Worked example 1: a US men's 9

Enter 9 with Men and US selected. The chart row is US 9 / UK 8 / EU 42 / 27.0 cm, which is 10.6 inches. Note the one-number gap to the UK figure and the fact that EU 42 is nowhere near double anything — Paris points simply count differently.

Worked example 2: a UK women's 5

Switch Category to Women and System to UK, then enter 5. The result is US 7 / UK 5 / EU 37.5 / 23.8 cm, about 9.4 inches. Here the US number sits two above the UK number, not one. Applying the men's rule to a women's shoe is the single most common conversion mistake, and it puts you a full size out.

Worked example 3: a measured foot of 26.7 cm

Choose Men, switch the system to foot length, and enter 26.7. The nearest charted length is 26.5 cm, which is US 8.5 / UK 7.5 / EU 41.5 — but the tool flags you as between sizes, because your foot sits 2 mm above that row and 3 mm below the 27.0 cm row. In practice that means ordering the 9. Half sizes are only about 4 to 5 mm apart, so a couple of millimetres genuinely decides which box to open.

Measuring your feet at home

Do it in the evening, when your feet are at their largest. Tape a sheet of paper to a hard floor with one edge against a wall, put on the socks you intend to wear with the shoes, and stand with your heel touching the wall and your weight on that foot. Have someone mark the paper at the tip of your longest toe — that is not always the big toe. Measure from the wall edge to the mark in centimetres, then repeat for the other foot.

Use the larger of the two numbers. Most people have a measurable difference between feet, and a shoe that fits the smaller one will pinch the other for the life of the pair. Do not add allowance yourself: retail charts already build roughly a centimetre of toe room into the last, so adding your own on top pushes you a size too large.

Men's reference chart

Brand variance, and how to buy online anyway

Two shoes marked EU 42 can differ by half a centimetre of usable length, and that is before you consider volume. Italian dress shoes tend to run narrow and short; American running shoes tend to run long; skate shoes and work boots often need a half size down because of thick insoles. Runners commonly go half a size up from their dress-shoe size to leave room for foot splay and swelling over distance.

Three habits make online buying survivable. First, always open the brand's own size chart and match it against your cm measurement rather than trusting the US number you have always worn. Second, if you already own a pair that fits, pull the insole out and measure it — insole length is the closest proxy for internal length you can get at home. Third, check the returns policy before you check out, because even a perfect conversion cannot predict width.

What this tool cannot tell you

It converts length only. Width (the D, 2E and EEE letters on US boxes, or F and G fittings in the UK), instep height and arch shape all affect fit at least as much as length does, and none of them appear in a size conversion chart. Kids' sizes carry an extra caveat: children's feet grow in bursts, so parents typically buy with about a centimetre of growing room, which the chart deliberately does not add for you. Specialist footwear — ski boots, cycling shoes, football boots — uses its own scales and should be fitted with the manufacturer's chart in hand.