Paris point

A Paris point is two thirds of a centimeter, 6.67 mm. EU shoe sizes count in Paris points: one whole EU size is 6.7 mm of length, and counting in Paris points is the same as multiplying a length in centimeters by 1.5.

The step is smaller than a UK or US size, which moves by a barleycorn of 8.47 mm. That is why EU and UK sizes never line up neatly, and why a chart that steps by foot length seems to skip a half size here and there.

On a size chart

Ruban Size's engine works from the foot: EU = 1.5 × foot length in cm + 2. The 2 is two Paris points, 1.33 cm on top of the foot. Each result is rounded to the nearest half size:

Brand charts differ. Ruban Size's Shoes template, written like a typical brand chart, puts EU 40 at a 25 cm foot where the formula says 39.5. Shoes are built on each brand's own lasts, so for a given shoe, the brand's chart wins.

In Ruban Size

On a shoe chart, Find my size adds the EU size to its "Usual equivalents (approximate)" line, with UK, US and JP. The shoe size converter gives the EU size for any foot length, for adults and children, and shoe size conversion chart from foot length has the table from 22 to 30 cm with the formulas behind it.