Generally speaking, portions for catered events include approximately one-third to one-half of a pound for the main entree or protein with a starch and vegetable on the side. The sides are portioned at approximately 4 ounces by weight or three-quarters of a cup by volume.
Portion sizes for catered events vary based on a variety of factors including style of service, such as buffet or plated, type of function, such as working lunch, reception or dinner, and type of food served. However, generally speaking, caterers calculate portions as follows: 5 to 8 ounces for the main dish and 4 ounces for each side. If serving hors d'oeuvres before the meal, assume guests will consume two to three pieces. Finally, approximately 4 ounces is generally sufficient for dessert.
For plated dinners, these portions can be followed precisely. However, for buffet service, it is often wise to slightly over-prepare to avoid having to prepare additional food during service. If the menu offers solely hors d'oeuvres, seven pieces per person is sufficient.
For alcoholic beverages, most guests consume approximately 1.5 drinks in an hour, or three drinks every two hours. Guests consume nonalcoholic beverages at a rate closer to two drinks per hour.