Hosting a party is tricky on its own, but it gets more complicated, the bigger the size of the party. There are a few ways to calculate how much food to serve, especially for parties where guests are not assigned their own plates. You want to serve enough so you don't waste a lot of food, but it is also undesirable to run out of food. Instead of guessing how much food is required per person, it is possible to use some math to calculate food amounts so you can prepare the right quantity.
Estimate the number of guests. Determine this number by counting the number of guests who have RSVP'ed, as well as the number of guests they're bringing. This is an important number because you will be able to intelligently estimate how much you need to serve and how much allowance you should give. Increase this number by 10 per cent to make sure you will have at least enough in case of unexpected guests.
Designate one pound of food for each guest. For example, if you're serving four items, such as appetizer, salad, main meal, and side, you can assign 1/4 pound of each item per person. Multiply 1/4 pound by the number of people, which should give you the number in pounds of how much to buy for each item. As a rule of thumb, each guest will consume approximately one pound of food. Of course, people of different sizes consume differently, but abiding by this rule will help you pinpoint a number.
Portion 170 to 227gr of meat per person if the meat is the main dish. If you are also serving a good amount of sides, 113 to 170gr will do the trick. According to Reason to Party, a party planning online guide, for pastas and sides, a pound will usually serve 8 to 10 people. For salads, people usually take about a handful, so estimate that a head of lettuce will serve five people.
Serve a variety of desserts so you can stretch main desserts to serve more people. For example, each person will take a slice of cake if it's the only dessert available, but if there are a few options, they may take just half a slice or none at all. For desserts that are easier to serve, such as cookies, serve each person two pieces. If you will be serving cake-like desserts, such as tiramisu, allow for each person to take 113gr of that item. To control the portions, you may want to slice the dessert beforehand so guests will know how much to take.
Learn how much beverage you should serve by knowing how many people each type of drink serves. Punch-style drinks serve 10 people per gallon. Alcoholic beverages are harder to measure because how much people drink depends on a variety of factors, such as the average age range of the guests and the day of the week. A bottle of beer equals one serving. If you have a large party, it might make more sense to serve punch-style drinks rather than individual bottles of beer or shots.
Keep in mind that the length of the event dictates how much food you are to serve. The longer the party, the greater the quantity of food will be needed.