On Running Women's Footwear Size Guide
On lists all footwear on its Australian site in US sizing, and Australian women's sizes are the same as US — a US 8 is an AU 8.
| US / AU | UK | EU | CM |
|---|---|---|---|
| 5 | 3 | 36 | 22 |
| 5.5 | 3.5 | 36.5 | 22.5 |
| 6 | 4 | 37 | 23 |
| 6.5 | 4.5 | 37.5 | 23.5 |
| 7 | 5 | 38 | 24 |
| 7.5 | 5.5 | 38.5 | 24.5 |
| 8 | 6 | 39 | 25 |
| 8.5 | 6.5 | 40 | 25.5 |
| 9 | 7 | 40.5 | 26 |
| 9.5 | 7.5 | 41 | 26.5 |
| 10 | 8 | 42 | 27 |
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.