Measuring your head with a fabric tape measure around the circumference of your head holding the tape just above your eyebrows and ears. 1" = 25mm
D3/D4 Helmet Size Chart
Head
Circumference
Inches 20 1/2 20 7/8 21 1/4 21 5/8 22 22 3/8 22 3/4 23 1/4 23 5/8 24 24 3/8 24 3/4 25 1/4 25 5/8
Hat 6 1/2 6 5/8 6 3/4 6 7/8 7 7 1/8 7 1/4 7 3/8 7 1/2 7 5/8 7 3/4 7 7/8 8 8 1/8
CM 52 53 54 55 56 57 58 59 60 61 62 63 64 65
D3 XS S M L XL XXL
D4 XS S M
L XL XXL