For chest size, measure under the arms level across back muscles and chest. Have the person take a deep breath when reading the measurement.

Men Chest (inches) 34 36 38 40 42 44 46 48 50 52 54 56
Size S S M M L L XL XL XXL XXL 3XL 3XL
Women Chest (inches) 30 32 33 34 35 37 38 40 42 44 46 48
Size XS XS S S M M L L XL XL XXL XXL
Youth Chest (inches) 22 24 26 28 30 32 34 36 38 40 42 44
Size XS XS S S M M L L XL XL XXL XXL