12.5 pounds of dry pinto beans are required for 150 servings of cooked beans. The standard serving size is one-half cup. One pound of dried pinto beans equals two cups of dried beans, or six cups of cooked beans.
If using canned beans, 50 fifteen-ounce cans of beans are required. Each can contains 1 ½ cups, or three servings. For people to be able to have seconds or a larger serving size, increase the amount of dried beans to 18.75 pounds and the amount of canned beans to 75 cans. This allows for every person to have a three-quarter cup of beans.