Men's UV top size guide - Quiksilver

Brand size	Chest circumference (cm)
XS	89 - 93
S	94 - 98
M	99 - 103
L	104 - 108
XL	109 - 112
XXL	112 - 117

To measure your chest size, place the measuring tape at the level of your armpits, at the widest point, and go around.