| Comp Helmet Size Mark | CE Liner (Pro-Dry Size Mark) | Circumference (cm) | Circumference (in) | Hat Size |
| XS | YS | 51 | 20 1/8 | 6 3/8 |
| XS | YL | 53 | 20 1/2 | 6 1/2 |
| S | S-M | 55 | 21 5/8 | 6 7/8 |
| M | S-M | 56 | 22 | 7 |
| M | M-L | 57 | 22 3/8 | 7 1/8 |
| L | M-L | 58 | 22 3/4 | 7 1/4 |
| L | M-L | 59 | 23 1/8 | 7 3/8 |
| XL | L-XL | 60 | 23 1/2 | 7 1/2 |
| XL | L-XL | 60.5 | 23 7/8 | 7 5/8 |
| XL | L-XL | 61.5 | 24 1/4 | 7 3/4 |