Shoe Size Converter

Foot length in centimetres is what all four systems are anchored to, and the constant doing the work is 0.847 cm per size step. That figure is the barleycorn — one third of an inch — which English shoemakers adopted as their increment in the fourteenth century and which every anglophone sizing system still inherits. Men's sizing here begins at 22.5 cm for a US 4 and adds a barleycorn per size, so the default US 10 resolves to 27.6 cm of foot. Women's uses the same increment from a lower origin of 21.0 cm at US 4, which is why the Category selector matters far more than it appears: a women's 8 and a men's 8 describe feet a centimetre and a half apart. The regional offsets are the crude part of the model.

UK is US minus a half for men and minus two for women, while EU is US plus 33, plus 31 or plus 16.5 depending on category. Those are linear stand-ins for the Paris point system, which does not track either anglophone scale perfectly, so a half-size disagreement at the extremes is normal. Results are rounded to the nearest half for US and UK, the nearest third for EU, and a tenth of a centimetre for length. Width is entirely absent — no B, D or EE — as is the manufacturer's last, which is the real reason two shoes marked with the same number fit differently. Japanese and Mondopoint sizes are already foot length in centimetres, so reach for the CM option there.