How sizes relate
All shoe sizes trace back to foot length in cm, with each system offset differently:
- EU ≈ (foot cm + 1.5) × 1.5 — the Paris point system
- US men ≈ EU − 33 · US women ≈ EU − 31 against the same foot
- UK ≈ US men − 1 (same for women after the gender offset)
- JP is simply foot length in cm (the Japanese Mondo system)
These are brand averages — Nike fits differently from Clarks. The reliable way to buy: measure your foot heel-to-toe in cm, use that as the anchor, and check the brand's own size chart if available.
Measuring your foot
Stand on a piece of paper against a wall, mark the tip of your longest toe and your heel, measure between the marks. Add ~0.5–1 cm of room (feet swell during the day; measure in the evening). Both feet — go with the larger.