Hat/Helmet Size Conversion Chart

Hat/Helmet Size Inches Centimetres
6 3/8" 20 51
6 1/2" 20 3/8" 52
6 5/8" 20 3/4" 53
6 3/4" 21 1/4" 54
6 7/8" 21 5/8" 55
7" 22 56
7 1/8" 22 3/8" 57
7 1/4" 22 3/4" 58
7 3/8" 23 1/8" 59
7 1/2" 23 1/2" 60
7 5/8" 23 7/8" 61
7 3/4" 24 1/4" 62
7 5/8" 24 5/8" 63
8" 25 64

To work out which helmet/hat size is correct, measure the circumference of the head. This length in centimetres/inches corresponds to the helmet/hat size. Please note, helmets that suit a large range (i.e. 6 7/8" - 7 5/8" or "one size fits most") are able to do so as they generally have thick padding which will compress to suit different sizes.