Adult O'Neills Size Guide- Training Wear 

Size Chest (IN) Waist (IN)
S 37/38 31/32
M 39/40 33/34
L 41/42 35/36
XL 43/44 38/40
2XL 45/46 42/44
3XL 47/48  

(Inside leg) 

Size Regular (IN) Skinny (IN)
S 30/31 30/31
M 31/32 30/31
L 31/32 30/31
XL 31/32 31/32
2XL 31/32 31/32

Shorts

Size Waist (IN) Inside Leg (IN)
S 32 4.5
M 34 4.5
L 36 4.5
XL 38 4.5
2XL 40 4.5