Why Shoe Sizes Differ by Country — mm, Paris Point, Barleycorn, Mondopoint
What the Korean and Japanese mm/cm sizes, the European Paris point, the British and American barleycorn and the international Mondopoint standard each measure, and why conversions between them slip by half a size.
The same foot is 260 in Korea, 8 in the US, 7 in the UK, and 40.5 or 41 in Europe. The numbers differ not simply because the units differ, but because the systems measure different things in the first place.
Systems that measure the foot: Korea, Japan, China, Mondopoint
Korea (KS M 6681), Japan (JIS S 5037), China (GB/T 3293.1) and the international Mondopoint standard (ISO 9407) are based on foot length. It means the shoe was made ‘to fit a person with a 260 mm foot’. Most use 5 mm steps, and the Japanese and Chinese standards also include width grades based on ball girth.
Mondopoint is a standard that allows foot length and foot width to be stated together in mm (e.g. 265/100). It appears more often in fields that need a precise fit, such as ski boots and military boots, than in everyday shoes.
Systems that measure the last: UK, US, Europe
UK, US and European sizes come from the length of the last (the foot-shaped form on which a shoe is made). The last is longer than the foot by the amount of toe room.
| System | One size step | Starting point |
|---|---|---|
| United Kingdom (UK) | 1/3 inch (barleycorn, about 8.47 mm) | Adult = 3 × last length (inch) − 25 |
| US men's | 1/3 inch | About 1 higher than UK |
| US women's | 1/3 inch | 1 (industry standard FIA) or 1.5 (customary scale) higher than men's |
| Europe (EU) | 2/3 cm (Paris point, about 6.67 mm) | Last length (cm) × 1.5 |
These formulas are the definitions compiled by Wikipedia. As they show, the steps themselves differ, so one UK size (8.47 mm) and one European size (6.67 mm) never line up exactly. UK 8 corresponds to about EU 41.9, so shops label it 42 or 41.5.
Three reasons for half-size slips
- Different allowance: how much longer the last is than the foot varies by brand and type of shoe. Running shoes allow a lot of room, dress shoes little.
- Rounding: whether EU 41.9 is labeled 42 or 41.5 differs by brand. Some brands use 1/3 steps such as 41⅓ and 42⅔.
- Simplification: size charts in Korean and Japanese shops often simplify to ‘10 mm = one US size’. An actual US size is about 8.5 mm, so the gap accumulates as feet get larger.
Why US men's and women's sizes differ
The US uses different numbering scales for men's and women's shoes. The footwear industry standard (FIA) defines the women's size as 1 larger than the men's for the same foot, but the older customary scale uses a difference of 1.5. Brands follow different conventions, so half-size confusion is common when a woman buys men's sneakers (or vice versa). SIZE ATLAS calculates +1, in line with the FIA definition and Korean retail charts.
Conclusion: use your foot length as the reference
Converting between systems several times adds up errors. The best approach is to take your own foot length (mm) as the reference and find the size for that foot length in the size chart of the brand you want to buy. When there is no brand chart, refer to the shoe size chart and the converter.
Size systems are approximate correspondences based on national standards and industry practice, and can differ by half to one size depending on brand, product and fabric. Always check the brand's own size chart before buying.