Approximate — actual fit varies by brand, region, and last shape. Use as a starting point, not an exact guarantee.
How it works
Enter a size you already know
Pick the system it's in — US Men's, US Women's, UK, EU, or a foot length in centimeters.
Read every other system at once
All five conversions update together, normalized through foot length.
Treat it as a starting point
Actual fit varies by brand and last shape, so it's worth checking a specific brand's own chart when it matters.
Shoe Size Conversion translates a size in one system — US Men's, US Women's, UK, or EU — into all the others, using foot length as the single unambiguous physical measurement every sizing system is ultimately built from.
US sizing follows the Brannock device convention: one full US size corresponds to exactly 1/3 inch of foot length, anchored at US Men's size 9 equaling 10.5 inches. EU sizing works differently, defined directly from foot length in centimeters via the historical "Paris point" system. Converting through foot length as the common unit — rather than trying to map every system directly onto every other one — is what keeps all the conversions internally consistent with each other.
None of this makes shoe sizing an exact science, though — actual fit still varies by brand, region, and the shape of a shoe's last, which is why sizing conversions are best treated as a reliable starting point rather than a substitute for trying a specific pair on or checking that brand's own size chart.