| Native Sizing | US Child | Approx. Fits | Europe | UK | JP/CM |
| C4 | 4 | 12 - 24 Months | 19 | 3 | 12 |
| C5 | 5 | 12 - 24 Months | 20 | 4 | 12.5 |
| C6 | 6 | 12 - 24 Months | 22 | 5 | 13.5 |
| C7 | 7 | 12 - 24 Months | 23 | 6 | 14 |
| C8 | 8 | 3 - 4 Years | 24 | 7 | 15 |
| C9 | 9 | 3 - 4 Years | 25 | 8 | 16 |
| C10 | 10 | 4.5 - 5 Years | 27 | 9 | 17 |
| C11 | 11 | 4.5 - 5 Years | 28 | 10 | 17.5 |
| C12 | 12 | 5.5 - 6 Years | 29 | 11 | 18.5 |
| C13 | 13 | 5.5 - 6 Years | 30 | 12 | 19.5 |
| J1 | 1 | 6.5 Years | 32.5 | 13 | 20 |
| J2 | 2 | 7 Years | 33.5 | 1 | 21 |
| J3 | 3 | 7.5 Years | 35 | 2 | 22 |