On Running Men's Footwear Size Guide
On lists all footwear on its Australian site in US sizing. Your Australian size is the same as your UK size, and On puts US only half a size above UK — so a US 10 is an AU 9.5.
| US | UK / AU | EU | CM |
|---|---|---|---|
| 7 | 6.5 | 40 | 25 |
| 7.5 | 7 | 40.5 | 25.5 |
| 8 | 7.5 | 41 | 26 |
| 8.5 | 8 | 42 | 26.5 |
| 9 | 8.5 | 42.5 | 27 |
| 9.5 | 9 | 43 | 27.5 |
| 10 | 9.5 | 44 | 28 |
| 10.5 | 10 | 44.5 | 28.5 |
| 11 | 10.5 | 45 | 29 |
| 11.5 | 11 | 46 | 29.5 |
| 12 | 11.5 | 47 | 30 |
| 12.5 | 12 | 47.5 | 30.5 |
| 13 | 12.5 | 48 | 31 |
| 13.5 | 13 | 48.5 | 31.5 |
Fit: On recommends going at least half a size up from your street shoe for running. On women's shoes run 1.5 US sizes larger than men's, so a men's US 7 is a women's US 8.5.