XS: chest 31.5-35in S: chest 35-37.5in M: chest 37.5-41in L: chest 41-44in XL: chest 44-48.5in XXL: chest 48.5-53.5in 3XL: chest 53.5-58in 4XL: chest 58-63in 5XL: chest 63-68in

S (Age 8-10) M (Age 10-12) L (Age 12-13) XL (Age 13-15)