If feeding beef to a crowd of 100 people an estimated 75 pounds of meat is needed. The portions of beef cuts, such as steak, per person is 3/4 of a pound.
When serving crowds the amount of meat per person can be slightly decreased it there will be a lot of side dishes available. If the beef is added to a dish like pasta the serving sizes are estimated at 1/4 to 1/3 pound per person.
If serving boneless beef 3 ounces per person is recommended. Plan on 1 pound per person if serving beef ribs, and 3 ounces per person when serving roast.