On vs ASICS shoe size
By the length each brand lists, On men's US 9 lines up with ASICS US 9. 6 of 15 men's sizes match the same US number.
Men's sizes
6 of 15 matched men's rows are the same US size. The median length difference is 0 mm on the size in cm scale. Every matched row lists the same length, so any difference below is in the size labels.
| On US | EU | UK | cm | ASICS US | EU | UK | cm | Diff |
|---|---|---|---|---|---|---|---|---|
| 7 | 40 | 6.5 | 25 | 6.5 | 39.5 | 5.5 | 25 | 0 |
| 7.5 | 40.5 | 7 | 25.5 | 7.5 | 40.5 | 6.5 | 25.5 | 0 |
| 8 | 41 | 7.5 | 26 | 8 | 41.5 | 7 | 26 | 0 |
| 8.5 | 42 | 8 | 26.5 | 8.5 | 42 | 7.5 | 26.5 | 0 |
| 9 | 42.5 | 8.5 | 27 | 9 | 42.5 | 8 | 27 | 0 |
| 9.5 | 43 | 9 | 27.5 | 9.5 | 43.5 | 8.5 | 27.5 | 0 |
| 10 | 44 | 9.5 | 28 | 10 | 44 | 9 | 28 | 0 |
| 10.5 | 44.5 | 10 | 28.5 | 11 | 45 | 10 | 28.5 | 0 |
| 11 | 45 | 10.5 | 29 | 11.5 | 46 | 10.5 | 29 | 0 |
| 11.5 | 46 | 11 | 29.5 | 12 | 46.5 | 11 | 29.5 | 0 |
| 12 | 47 | 11.5 | 30 | 12.5 | 47 | 11.5 | 30 | 0 |
| 12.5 | 47.5 | 12 | 30.5 | 13 | 48 | 12 | 30.5 | 0 |
| 13 | 48 | 12.5 | 31 | 14 | 49 | 13 | 31 | 0 |
| 13.5 | 48.5 | 13 | 31.5 | 14.5 | 49.5 | 13.5 | 31.5 | 0 |
| 14 | 49 | 13.5 | 32 | 15 | 50.5 | 14 | 32 | 0 |
Sources: On, www.on.com (checked 2026-10-24) · ASICS, www.asics.com (checked 2026-10-24)
Women's sizes
6 of 14 matched women's rows are the same US size. The median length difference is 0 mm on the size in cm scale. Every matched row lists the same length, so any difference below is in the size labels.
| On US | EU | UK | cm | ASICS US | EU | UK | cm | Diff |
|---|---|---|---|---|---|---|---|---|
| 5 | 36 | 3 | 22 | 4.5 | 35 | 2.5 | 22 | 0 |
| 5.5 | 36.5 | 3.5 | 22.5 | 5 | 35.5 | 3 | 22.5 | 0 |
| 6 | 37 | 4 | 23 | 6 | 37 | 4 | 23 | 0 |
| 6.5 | 37.5 | 4.5 | 23.5 | 6.5 | 37.5 | 4.5 | 23.5 | 0 |
| 7 | 38 | 5 | 24 | 7 | 38 | 5 | 24 | 0 |
| 7.5 | 38.5 | 5.5 | 24.5 | 7.5 | 39 | 5.5 | 24.5 | 0 |
| 8 | 39 | 6 | 25 | 8 | 39.5 | 6 | 25 | 0 |
| 8.5 | 40 | 6.5 | 25.5 | 8.5 | 40 | 6.5 | 25.5 | 0 |
| 9 | 40.5 | 7 | 26 | 9.5 | 41.5 | 7.5 | 26 | 0 |
| 9.5 | 41 | 7.5 | 26.5 | 10 | 42 | 8 | 26.5 | 0 |
| 10 | 42 | 8 | 27 | 10.5 | 42.5 | 8.5 | 27 | 0 |
| 10.5 | 42.5 | 8.5 | 27.5 | 11 | 43.5 | 9 | 27.5 | 0 |
| 11 | 43 | 9 | 28 | 11.5 | 44 | 9.5 | 28 | 0 |
| 12 | 44 | 10 | 29 | 13 | 46 | 11 | 29 | 0 |
Sources: On, www.on.com (checked 2026-10-24) · ASICS, www.asics.com (checked 2026-10-24)
Convert your exact size
What a chart comparison cannot tell you
Both tables come from brand-wide size charts. They do not capture the shape of a particular model, its width or how it wears. Check the fit notes on the On size chart and the ASICS size chart before you buy.