What size boneless rib roast will serve 20 people? How about a bone-in roast?!
Answers: My hubby the butcher just walked in. He said 15 lbs for the boneless and 20 lbs for the bone-in. If you want to give people a hunk then lb a person but if you cook the roast and slice thin you can stretch it. There will be shrinkage when you cook it. The thing is with prime rib it's so good, that people will probably want seconds.
It depends on if you have a lot of side dishes etc. If the rib roast is pretty much the main part of the meal, you want just over 1 lb per person. If you have a lot of other foods, half a pound per person is probably fine. You just can't count the bone weight. Also consider who you are feeding - seniors, little kids or cheerleaders you can go with less. All adults, especially like a football team of guys, go with more.
A rib roast comprises of seven ribs starting from the shoulder (chuck) down the back to the loin. Each rib feeds about two people, so if you have a party of eight, buy and cook a four rib roast. So you can figure from there.
Then,bone-in rib roast,1 pound per serving will serve up to 4 adults, 8 adults, or 12 adults respectively.
7 pounds will cover it,but slice very thin to serve.About a 1/3 of a pound per person gets it.