Asics US 9 corresponds to a 270 mm foot length, which is Korean size 270, EU 42.5 and UK 8.
True to size, and as a Japanese brand it labels in millimetres by default. The fit is standard to slightly wide.
Because Asics labels in millimetres, it produces the least size confusion of the big brands. Gel-Kayano and Gel-Nimbus fit true, though runners commonly take half a size up to allow for feet swelling over distance.
Asics Full size chart
| US | UK | EU | mm (foot length) | KR (Korea) |
|---|---|---|---|---|
| 6 | 5 | 38.5 | 240mm | 240 |
| 6.5 | 5.5 | 39 | 245mm | 245 |
| 7 | 6 | 40 | 250mm | 250 |
| 7.5 | 6.5 | 40.5 | 255mm | 255 |
| 8 | 7 | 41 | 260mm | 260 |
| 8.5 | 7.5 | 42 | 265mm | 265 |
| 9 | 8 | 42.5 | 270mm | 270 |
| 9.5 | 8.5 | 43 | 275mm | 275 |
| 10 | 9 | 44 | 280mm | 280 |
| 10.5 | 9.5 | 44.5 | 285mm | 285 |
| 11 | 10 | 45 | 290mm | 290 |
| 11.5 | 10.5 | 45.5 | 295mm | 295 |
| 12 | 11 | 46 | 300mm | 300 |
How it fits
How to measure your foot
Stand with your heel against a wall on a sheet of paper and mark the tip of your longest toe. Wall to mark is your foot length in millimetres. Measure in the evening โ feet swell slightly through the day, and that is the size you actually wear.
Most people have two slightly different feet, so measure both and use the longer one. Trainers are normally chosen 5-10 mm longer than the foot itself.