Dear Lisa: Is there any rule of thumb for figuring out the amount of meat to buy when cooking for a crowd? I am in charge of a fajita dinner for our church, and I don't have any idea how much we need to prepare. Any help you can provide would be most appreciated. -- M.S.

Dear M.S.: Calculating the amount of food to buy is simple math. First, you need to know that 3 ounces of cooked meat is considered a serving. For fajitas, that would make about two filled tortillas per person.

You will need about 4 ounces of uncooked meat to yield 3 ounces of cooked beef, pork or chicken. In other words, plan on 1 pound of boneless meat for every four people. Of course, you need to consider other factors such as appetites (are the guests linebackers or Girl Scouts?) and the number of side dishes offered, which can reduce or increase the amount of protein you'll need.

You can plan on about 1 tablespoon of cheese, sour cream and/or guacamole per tortilla. How do you buy that? There are 16 tablespoons in a cup, so you can figure that 1 pint (2 cups) of sour cream or guacamole will yield 32 servings. One pound of grated cheese will yield about 64 (1-tablespoon) servings.

What if the entree you're serving contains bones? Then consider these guidelines: for chicken wings or spare ribs, plan on 1 pound per person. For semi-boneless cuts, such as prime rib roast, chuck roast or chicken pieces, plan on 1/2 to 3/4 pound per person.

Finally, to help control serving size, you can employ a few tricks used by caterers. Use servers to portion out the meat, and/or place the entree at the end of the serving line, when the diner's plate is almost full.

* Lisa Fritz, a longtime Bryan food and nutrition educator, answers readers' questions about food, cooking and recipes. Her e-mail address is cheflisa525@yahoo.com.