Please see below for approximate measurements:

Trunk Size XS S M L XL 2XL
Relaxed Waist - Measured flat  12" 12.5" 13.5" 14" 15" 16"
Extended Waist - Measured Flat 15.5" 16" 17" 18" 18.5" 19.5"
Inside Leg - Measured flat from crotch to bottom hem 7" 8" 8" 9" 9" 10"
Bottom Leg Opening - Measured from edge to edge 8" 8.5" 9" 9" 9.5" 10"