One of the challenges when planning an event for a large group is calculating how much food you need to prepare. You don't want the disaster of running out of food before everyone has had a chance to eat. You can avoid this by using the proper techniques to determine the food quantities for a large event. You will then be able to calculate how much food you need for the appetizers, main entree, side dishes and dessert.

Get an almost accurate number of how many people you will be feeding. It will be impossible to know exactly how many people will actually show up, but use your guest list and the number of people who sent in a RSVP to get an almost accurate head count.

Take the number of your guest list and multiply it by three to calculate how many servings you will need for the appetizers. A rule of thumb is to always calculate a big group meal as though it is a buffet, even if it is a sit down affair. People tend to go back for more servings or pile more food on their plate when they are at a buffet. Calculating three servings of appetizers for each person will ensure that you have enough for everyone.

Plan to use four heads of lettuce for every five guests if you are serving green salads. For other salads, such as macaroni or potato, have at least a gallon for every group of 25. For instance, you will need two gallons of potato salad for a group of 50 people.

Calculate 4 ounces of pasta for every guest, if it is being served as a main course. If you have a pasta dish as a side dish, then only calculate a 2-ounce serving for each guest. Use the same 2-ounces-per-guest measurement for all of your side dishes.

Estimate 6 ounces of fish for each guest, if you are serving it as a main course. Other meat's servings vary based on the type of meat you are serving. A 18-pound turkey, 12-pound roast or 7-pound boneless ham is enough for 25 to 30 people. For a group larger than this, calculate based on the group of 30. For example, for 60 people, use a 24-pound beef roast.

Calculate one serving of dessert for every guest if you are serving cake, pie or cobbler. For cookies, brownies or miniature desserts, estimate three pieces for each guest.

Plan to serve one drink per guest for each hour. Drinks are tricky and you should adjust this number based on the crowd. A tailgating party may require more drinks than a baby shower. Start with having four cups for each guest unless it is a relatively short event. For six guests, have about a pound of ice available.