How to use the Shoe Size
- Stand on paper against a wall and mark your longest toe.
- Measure heel to mark in centimetres.
- Enter the length and select men's or women's sizing.
- Add 0.5–1 cm of toe room before converting.
How the calculation works
UK sizing uses the barleycorn, one third of an inch, with size zero at 4 inches; US men's sizes run one higher than UK, and US women's roughly 1.5 to 2 higher than US men's. EU sizing uses the Paris point of two thirds of a centimetre, applied to last length rather than foot length, which is why EU conversions vary by up to a full size between brands. Japanese sizing simply states foot length in centimetres, which is the least ambiguous system of the four.
Length is only half of fit. Width grades — B, D, EE and so on — differ by about 4 mm per grade, and a foot in the wrong width will never fit properly regardless of length. Feet also swell up to 5% during the day and grow slightly with age and pregnancy, so measure both feet in the evening and size to the larger one. Running shoes are usually bought half to a full size up to allow for swelling over distance.
UK = (foot inches × 3) − 23 ; US men = UK + 1 ; EU ≈ (foot cm + 1.5) × 1.5Source: Barleycorn (UK/US) and Paris point (EU) shoe sizing systems; Mondopoint foot-length standard.
Worked example
A men's foot measuring 27.2 cm.
- Add 0.7 cm toe room: 27.9 cm effective length.
- In inches = 10.98, so UK = (10.98 × 3) − 23 = 9.9, round to UK 10.
- US men = 11.
- EU ≈ (27.2 + 1.5) × 1.5 = 43.
UK 10, US 11, EU 43 — with brand variation of up to half a size either way.
Frequently asked questions
Why do sizes differ between brands?+
EU sizing measures the last, not the foot, and every brand's last differs slightly.
When should I measure my feet?+
In the evening, when feet have swollen to their largest.
Should running shoes be bigger?+
Usually half to a full size up, since feet swell over distance.
What if my feet are different sizes?+
Very common. Fit the larger foot and pad the smaller one.
Last reviewed August 31, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.