A small metal tape measure, or a cloth tape may be used to make your initial measurement.
The circumference of the head should be measured at a point approximately one inch above the eyebrows in front, and at a point in the back of the head that results in the largest possible measurement. Take several measurements, to make sure you have the largest one.
PLEASE NOTE THAT THIS IS A ROUGH GUIDE AND NOT EXACT. THE SHAPE OF YOUR HEAD IS AS IMPORTANT AS THE MEASUREMENT WHICH MAY AFFECT FINAL FIT!
Racequip Sizing Chart
| Size | Inches | Centimeters | Hat Size |
| XX-Small | 20 to 20 1/2 | 51 to 52 | 6 3/8 to 6 1/2 |
| X-Small | 20 3/4 to 21 1/4 | 53 to 54 | 6 5/8 to 6 3/4 |
| Small | 21 1/2 to 22 1/8 | 55 to 56 | 6 7/8 to 7 |
| Medium | 22 3/8 to 22 7/8 | 57 to 58 | 7 1/8 to 7 1/4 |
| Large | 23 1/8 to 23 3/4 | 59 to 60 | 7 3/8 to 7 1/2 |
| X-Large | 24 to 24 1/2 | 61 to 62 | 7 3/4 to 7 5/8 |
| XX-Large | 24 3/4 to 25 1/4 | 63 to 64 | 7 7/8 to 8 |