Patrick, i cook 18 pounders for the most part, 20 would be fine. one thing that can make a difference is where you bought it, the free range style birds i get are sometimes longer than the store bought stuff, one farms free range can be different from another as well. i stick with 18 pounders because theres no surpises for me year to year and because thars about max for my indoor small ovens as well.
