How shoe sizing systems differ
The UK system starts from a child size 0 at roughly 4 inches and increments by one-third of an inch per size. US sizing is offset from UK by roughly one size for men and two sizes for women, though the increments are the same. The EU system uses Paris points, where each size equals two-thirds of a centimetre. Japanese sizing uses centimetres directly, measuring foot length in whole or half centimetre steps.
Half sizes exist in UK, US, and JP systems but not always in EU sizing, where adjacent whole sizes cover a similar range. Width fittings add another dimension that varies by brand and region.