Hong Life CalculatorsUnderstanding the shoe size converter — concept and principle
This converter starts from foot length as used on Korean shoe labels (mm) and shows the matching Japanese size in cm and approximate US men's, US women's, UK and EU sizes. It is useful when you shop on overseas websites, buy imported sneakers, or need to tell a friend abroad what size to buy you.
How it is calculated
Korea labels shoes by foot length in millimetres and Japan by the same length in centimetres, so 260 mm = 26 cm. The other systems are approximated from foot length L:
- US men ≈ 3 × L (inches) − 22, where L (in) = L (mm) ÷ 25.4.
- US women ≈ US men + 1.5.
- UK ≈ US men − 0.5.
- EU ≈ 1.5 × (L in cm + 1.5).
Results are rounded to the nearest half size and shown for 220–300 mm in 5 mm steps.
The principle
The Korean and Japanese labels, like the international Mondopoint idea (ISO 9407), describe the foot itself, which is the most direct measure. The older systems describe the shoe's last instead. UK and US sizes count in barleycorns of 1/3 inch (about 8.47 mm), so one full size is about 8.5 mm of length, and the "3 × inches" term reflects that. The EU system counts in Paris points of 2/3 cm (about 6.67 mm), which gives the factor 1.5 per centimetre, and the extra 1.5 cm is an allowance for the last being longer than the foot. Each scale also has a different zero point, which is why the conversion is approximate.
Worked example
Default input: foot length 260 mm.
- Japan: 260 mm ÷ 10 = 26 cm.
- Length in inches: 260 ÷ 25.4 = 10.24 in.
- US men: 3 × 10.24 − 22 = 8.71 → 8.5.
- US women: 8.71 + 1.5 = 10.21 → 10. UK: 8.71 − 0.5 = 8.21 → 8.
- EU: 1.5 × (26 + 1.5) = 41.25 → 41.
- Result: 260 mm = 26 cm, US men 8.5, US women 10, UK 8, EU 41.
How to read the result
One full US or UK size is about 8.5 mm, and one EU size about 6.7 mm, so a 5 mm step in Korean sizes moves you a little over half a US size. If your foot falls between sizes, or one foot is longer, go by the longer foot and consider width as well as length. Running and hiking shoes are often chosen a half size larger to allow for swelling.
Common mistakes
- Measuring without standing; the foot spreads under body weight.
- Measuring in the morning; feet are usually slightly larger in the evening.
- Using the US men's figure for women's shoes, which differs by about 1.5 sizes.
- Treating a brand's chart as universal; lasts and fits differ between makers.
FAQ
Frequently asked questions
What US size is 260 mm?
About US men 8.5 or US women 10, UK 8 and EU 41.
How do I measure my foot length?
Stand on paper with your heel against a wall, mark the tip of the longest toe and measure from the wall in mm.
Why does my size differ between brands?
Each brand designs shoes on its own last, and many round sizes differently.
Sources: ISO 9407, Shoe sizes — Mondopoint system of sizing and marking · Brannock Device Company, Brannock foot-measuring scale