You can figure roughly a 25% loss. That's for the whole bird. Then you have the weight of the inedible bones. Overall the yield is about 50%.
A friend tried a number of business ventures, most of which didn't work out. He was quite meticulous to the point of being suffering from OCD. One was a sandwich business for a barroom. He was quite shocked when a
10 pound beef roast didn't yield the number of 4 ounce sandwich portions he had calculated after cooking. He found that buying frozen pre-cooked roasts from a restaurant supply was more economical.Then there was the pizza parlor... The night before the grand opening I found him sitting on the floor drinking beer and close to tears. 'I made a pizza and it was so bad the dog wouldn't eat it.'