| SIZE | INCHES | CM | HAT SIZE |
| X-SMALL | 19 1/8 - 20 | 49-51 | 6 - 6 3/8 |
| SMALL | 20 1/8 - 21 | 52-54 | 6 1/2 - 6 3/4 |
| MEDIUM | 21 1/8 - 22 | 54-56 | 6 3/4 - 7 |
| LARGE | 22 1/8 - 23 | 56-58 | 7 - 7 1/4 |
| X-LARGE | 23 1/8 - 24 | 59-61 | 7 3/8 - 7 5/8 |
| XX-LARGE | 24 1/8 - 25 | 62-64 | 7 3/4 - 8 |
| XXX-LARGE | 25 1/8 - 25 3/4 | 64-66 | 8 - 8 1/4 |
| Helmet Sizes | Head Circumference (Inches) | Head Circumference (Metric) | Hat SIzes |
| 3XS | 16 1/8 - 17 | 41 - 43.2 cm | 5 1/8 - 5 2/5 |
| 2XS | 17 1/8 - 18 | 43.5 - 45.7 cm | 5 4/9 - 5 3/4 |
| XS | 18 1/8 - 19 | 46 - 48.3 cm | 5 3/4 - 6 |
| S | 19 1/8 - 20 | 48.6 - 50.8 cm | 6 - 6 3/8 |
| M | 20 1/8 - 21 | 51.5 - 53.3 cm | 6 2/5 - 6 2/3 |
| L | 21 1/8 - 22 | 53.7 - 55.9 cm | 6 5/7 - 7 |
| XL | 22 1/8 - 23 | 56.2 - 58.4 cm | 7 - 7 1/3 |
| 2XL | 23 1/8 - 24 | 58.7 - 61 cm | 7 1/3 - 7 2/3 |
| 3XL | 24 1/8 - 25 | 61.3 - 63.5 cm | 7 2/3 - 8 |
| 4XL | 25 1/8 - 26 | 63.8 - 66 cm | 8 - 8 2/7 |