Weighing meat for P90X

So........I have been working on figuring out weighing my chicken on P90X......Of the seven servings of protein, I am using six in chicken. I weigh it raw to get 6-3 oz servings for 6 days for 7 lbs, after I cook it it only weighs about 4 lbs. so I have calculated that into 2 meals for a total of 11 oz of chicken. Does that sound right to you all?