How Many Pounds of Prime Rib Roast Do You Need to Feed 12 People?

A six- to nine-pound prime rib roast feeds 12 people, depending on the type of meal planned. If the meat is part of a large buffet, six pounds suffice, but if it is the main course of a holiday or dinner party meal, a nine-pound roast is needed.

A convenient formula for figuring the amount of meat necessary is to count 1/2 pound of prime rib roast per person for a buffet and 3/4 pound per person for a main course, reports. The Food advises calculating two people per rib, which roughly comes out to one pound per person served.