How To Calculate Roast Beef Per Person. How to calculate roast beef per person. A serving of beef is about 4 ounces per person.
When serving hamburgers, allow for 2 burgers per person (at 4 ounces per burger) 8 ounces total; Meat portions are generally 25% smaller at lunch. In general, this could be anywhere from 4 ounces per person up to 12 ounces or even more for big eaters.