Why Sizes Do Not Travel Well
Clothing and shoe sizes are regional conventions rather than measurements, and each system was built on a different basis. A UK shoe size counts in barleycorns from a different starting point than a US one; European sizes measure the last in Paris points; Japanese and Korean sizes state the foot length in millimetres, which is the only system that says what it means.
This converter maps between them so you can start from the size you know. It works for shoes and for clothing, in both directions.
How to Convert Your Size
Converting a known size is quick; getting a reliable one is worth five minutes with a ruler.
- Pick the category, shoes or clothing, and the system your current size is in.
- Enter the size you already know fits you in that system.
- Read the equivalent across the other systems.
- For shoes, measure your foot as well: stand on paper, mark heel and longest toe, and measure the distance in millimetres. That length is directly comparable to Japanese and Korean sizing.
- Measure in the evening, when feet are at their largest, and measure both feet, most people have one slightly longer, and that is the one to size for.
- Check the result against the brand’s own size chart before buying, since brands within a country vary more than the conversion between countries.
Where Conversions Break Down
Shoe conversions are approximate because the underlying systems do not line up in even steps. The gap between UK and US men’s sizing is a consistent one size, but half sizes fall differently, and women’s conversions carry an additional offset that varies by manufacturer. A converted size is a starting point for which size to try, not a guarantee of fit.
Clothing is looser still. Letter sizes have drifted over decades, vanity sizing means a modern size 10 is considerably larger than a size 10 from the 1980s, and cut varies far more than nominal size. Body measurements are the only stable reference, which is why the better retailers publish a chest, waist and hip chart rather than only letters.
Shoe Size Conversion
Approximate men’s equivalents. Foot length is the anchor: everything else is a convention layered on top of it.
| Foot length | US | UK | EU | JP / KR |
|---|---|---|---|---|
| 240 mm | 6 | 5.5 | 39 | 240 |
| 245 mm | 6.5 | 6 | 39.5 | 245 |
| 250 mm | 7.5 | 7 | 40.5 | 250 |
| 255 mm | 8 | 7.5 | 41 | 255 |
| 260 mm | 8.5 | 8 | 42 | 260 |
| 265 mm | 9.5 | 9 | 43 | 265 |
| 270 mm | 10 | 9.5 | 44 | 270 |
| 275 mm | 10.5 | 10 | 44.5 | 275 |
| 280 mm | 11 | 10.5 | 45 | 280 |
| 285 mm | 11.5 | 11 | 45.5 | 285 |
Women’s sizing follows the same lengths but different labels, a US women’s size is commonly about 1.5 above the men’s number for the same foot. EU sizes vary by up to half a size between manufacturers, so treat them as the least precise column.
Fit Is More Than Length
Width is the dimension conversions ignore entirely, and it is often what makes a correctly sized shoe uncomfortable. Some manufacturers publish widths (D, E, EE, or narrow through wide); many do not, and a brand whose last is narrow will feel tight at the right length. If shoes in your size regularly pinch across the ball of the foot, width rather than length is the thing to change.
It is also worth sizing for the shoe’s purpose. Running shoes are usually bought half a size up because feet swell over distance, while a dress shoe at that size would slip at the heel. Sizing up to fit a thick sock is a similar adjustment, and both are reasons a converted number may not be the number you order.