Shoe Size Conversion Chart

Foot length is measured heel to longest toe, standing, with the weight on the foot.

The US and UK scales run two sizes apart for women, not one.

US kids’ sizes restart at 1 after 13, marked C for child and Y for youth. UK sizes restart at the same point, one number lower.

Both systems measure in barleycorns, one third of an inch, and both add a small allowance to the foot length before assigning a number. The UK scale starts its count lower down, so the same shoe gets a number one lower in the UK than in the US for men.

For women the gap doubles to two sizes. There is no principled reason for this; it is a historical artefact of the two markets developing women’s ranges separately. It is also the single most common shoe-size mistake, because someone who knows the men’s rule applies it to women’s shoes and orders a size too small.

Stand on a sheet of paper with your heel against a wall, in the socks you would wear with the shoes, and mark the tip of your longest toe. That is not always the big toe. Measure heel to mark in centimeters, do both feet, and use the larger figure.

Measure at the end of the day. Feet swell over the course of a day by up to half a size, so a morning measurement produces shoes that pinch by evening. Add about 1 cm of toe room for everyday shoes, more for running.

Width is not in any of these systems except as a US letter code, D being standard for men and B for women. A correctly sized shoe in the wrong width fits worse than a half size out in the right one.

Brand drift is real and unevenly distributed. Athletic brands tend to run small, so a half size up is common; Italian dress shoes often run narrow and long. When a brand publishes its own chart, that chart beats this one.