O'Neill Sizing Guide for Youth Gloves

Size	Hand Length (cm)	Circumference (cm)
S	14.5 - 15.5	15.2 - 16.5
M	15.2 - 16.5	15.9 - 17.1
L	15.9 - 17	16.5 - 17.5
XL	16.5 - 17.5	17.1 - 18.4