TO DETERMINE HAT SIZE, measure around your head just above the eyebrows and ears.
Take this dimension in inches and divide by 3.14. This will give your hat size.
EXAMPLE
For a head measuring 23.5 inches,
dividing 23.5 by 3.14 yields 7.48
7.48 equates to a 7-1/2 hat size
See chart below to convert from hat size to helmet size and to choose a helmet color.
| NUMBER | COLOR | NUMBER | NOMINALSIZE | HAT SIZE | |
| 1 | WHITE | 6 | XX-LARGE | 7-5/8 & UP | |
| 2 | RED | 7 | X-LARGE | 7-3/8 to 7-5/8 | |
| 3 | BLUE | 8 | LARGE | 7-1/8 to 7-3/8 | |
| 4 | BLACK | 9 | MEDIUM | 6-7/8 to 7-1/8 | |
| 5 | GRAPHITE | 10 | SMALL | 6-5/8 to 6-7/8 |