| helmet | size | measurement | metric |
| junior | 5-1/4 to 6-1/2 | onesize fits average up to age 9 |
n/a |
| xsmall | 6-5/8 to 6-3/4 | 20-7/8 to 21-1/4 | 53 to 54 |
| small | 6-7/8 to 7 | 21-5/8 to 22 | 55 to 56 |
| medium | 7-1/8 to 7-1/4 | 22-3/8 to 22-3/4 | 57 to 58 |
| large | 7-3/8 to 7-1/2 | 23-1/8 to 23-1/2 | 59 to 60 |
| xlarge | 7-5/8 to 7-3/4 | 23-7/8 to 24-1/4 | 61 to 62 |
| xxlarge | 7-7/8 to 8 | 24-3/4 to 25-1/8 | 63 to 64 |
