How this calculator works
Shoe sizing has no single global standard. This calculator uses the standard equivalence between foot length and each major sizing system: US Men's, US Women's, UK, EU/Continental, and CM (Mondopoint, the ISO 9407 system that states foot length in millimeters directly). Choose a known size in any system, or switch to foot-length mode and enter a length in centimeters or inches.
Two facts matter more than any conversion table here. First, foot length in cm or mm is the only measurement that means the same thing everywhere; every other system is a rounded label built on top of it. Second, real shoe brands use their own lasts (the foot-shaped forms shoes are built on) and their own rounding conventions, so an actual brand's labeled size can differ from this standard conversion by up to a full size. When fit matters, check the specific brand's own size chart or measure your foot length and compare it to the brand's stated foot-length range.
The conversions used here
US Men's size = 3 × (foot length in inches) − 22UK size = US Men's size − 1US Women's size (common scale) = US Men's size + 1.5EU/Continental size = 1.5 × (foot length in cm) + 2CM (Mondopoint) = foot length in millimetersUS Men's and UK sizes both increase by one full size per 1/3 inch (about 8.47 mm) of foot length. EU sizes increase by one 'Paris point' per 2/3 cm (about 6.67 mm) of foot length — a different, unrelated step size, which is why US/UK and EU sizes never line up on exactly the same fractions. The published reference table also lists a slightly narrower US Women's scale (Men's + 1) alongside the more commonly used Men's + 1.5 scale used here.
Worked example: US Men's size 9
- Foot length: (9 + 22) × 25.4 ÷ 3 ≈ 262.5 mm, or about 26.25 cm (10.33 in).
- UK size: 9 − 1 = 8.
- US Women's size (common scale): 9 + 1.5 = 10.5.
- EU size: 1.5 × 26.25 + 2 ≈ 41.4, commonly labeled as EU 41 or 41.5 depending on the brand's rounding.
Frequently asked questions
Why do US and EU sizes never convert to a clean matching fraction?
US/UK sizes step in units of 1/3 inch of foot length, while EU sizes step in units of 2/3 cm. Those two step sizes are not simple multiples of each other, so a chart that lines up both systems always needs some rounding at various points.
Is US Women's size always Men's size plus 1.5?
That is the most commonly used consumer convention, and the one this calculator uses. Some official reference tables use Men's plus 1 instead (sometimes labeled the 'FIA' scale). Either way, women's and men's shoes of the 'same' labeled size are not built on the same last, so fit still varies by brand.
Why is measuring my foot length better than looking up my usual size?
Your 'usual size' already reflects one specific brand's rounding and last shape. Foot length is the one number that translates directly and consistently into any sizing system, which is why this calculator offers a foot-length mode.
What is Mondopoint?
Mondopoint (ISO 9407) is an international sizing standard that states shoe size directly as foot length in millimeters, sometimes with a width code added. A Mondopoint size of 270 fits a 270 mm (27.0 cm) foot.
Does this account for width?
No. All the systems here describe length only. Width sizing (like narrow/regular/wide, or letter codes such as B or D) is a separate, brand-specific measurement not covered by this calculator.