How it works
Everything is derived from one number, foot length in centimetres. Japanese sizing is that length unchanged. US men = length − 18.5, US women = US men + 1.5, UK = US men − 1, and Chinese = (length × 2) − 10. The EU figure adds 1.5 cm of shoe allowance and multiplies by the Paris-point factor of 1.5, rounded to the nearest half size. A 26.0 cm foot therefore returns US men 7.5, US women 9, UK 6.5, EU 41.5, JP 26 and CN 42.
Measure standing, at the end of the day, heel to longest toe, and add 5 to 10 mm of toe room before entering the figure, because the tool converts what you type and adds no allowance of its own beyond the fixed 1.5 cm inside the EU formula. Category changes only the headline result: Men shows US men, Women adds 1.5, Kids adds 12.5. In Known size mode the same equations run backwards from the value and system you choose.
These are linear approximations. US and UK sizes really step by a third of an inch, about 0.85 cm, whereas this formula moves a full size per centimetre, so results drift from a brand's own chart the further you go from the middle of the range; expect to be within roughly half a size rather than exact. Width is not modelled at all, the Kids figure is a flat +12.5 offset, and the comparison table always lists adult rows even when Kids is selected.
Frequently asked questions
What EU shoe size is a 26 cm foot? +
EU 41.5. The tool adds 1.5 cm of shoe allowance to your foot length and multiplies by 1.5, rounding to the nearest half size. The same foot returns US men 7.5, US women 9, UK 6.5, JP 26 and CN 42.
How do I find my Japanese shoe size? +
Japanese sizes are simply foot length in centimetres, so the JP row repeats whatever you measured: a 26 cm foot is JP 26. That makes it the least ambiguous system to buy in, and it is the value every other conversion here is built from.
How do US men's, US women's and UK sizes relate? +
US women is US men plus 1.5, and UK is US men minus 1, so a US men 8 is a US women 9.5 and a UK 7. The Category select applies those same offsets to the headline result while the table lists all of them.
How should I measure my foot length? +
Stand with weight on the foot, at the end of the day when feet are at their largest, and measure heel to longest toe. Add 5 to 10 mm of toe room before entering the number, and measure both feet, then buy for the larger one.
Do Nike and Converse fit true to size? +
The built-in brand notes flag Nike as running half a size small and Converse half a size large, with Adidas, Vans and New Balance true to size and Birkenstock sold in EU sizes only. Adjust the converted number by half a step accordingly.
Foot length is the only stable input
Shoe sizing is not standardised between regions and is not reliably consistent between manufacturers within one. Measuring foot length in millimetres and converting from that is more reliable than converting between labelled sizes, because the length is a fact and the label is a manufacturer's choice.
Japanese sizing is the most transparent system in common use, since it is stated directly in centimetres of foot length.
Width, last shape and measuring properly
Length is only one dimension. Width is sized separately in some systems and ignored in others, and last shape — the form the shoe is built around — differs enough between brands that two shoes of identical stated size fit quite differently. A brand that suits one foot shape may never fit another regardless of size.
Feet also change: they swell through the day, so measuring in the evening gives a more useful figure, and they lengthen and widen over years and after pregnancy.
Most people have one foot slightly larger than the other, and shoes should be fitted to the larger one. Allow roughly a centimetre of space beyond the longest toe for walking shoes and more for running.
