helmet size measurement metric
youth sm 5-7/8 to 6 18-5/8 to 19 47-48
youth md 6-1/8 to 6-1/4 19-3/8 to 19-3/4 49-50
youth lg 6-3/8 20-1/8 51-52
xsmall 6-3/8 20-7/8 to 21-1/4 53 to 54
small 6-7/8 to 7 21-5/8 to 22 55 to 56
medium 7-1/8 to 7-1/4 22-3/8 to 22-3/4 57 to 58
large 7-3/8 to 7-1/2 23-1/8 to 23-1/2 59 to 60
xlarge 7-5/8 to 7-3/4 23-7/8 to 24-1/4 61 to 62
xxlarge 7-7/8 to 8 24-3/4 to 25-1/8 63 to 64