Family is gathering at my house for Christmas supper this year. How big of a turkey do I need? There will be about 14 adults and 5 children.--Emily
The size of turkey you need depends on three major questions. The first one you have answered -- how many people will there be. Next, you need to decide on portion size. Health adults need only about 3 to 6 ounces (85 - 170 grams) of meat in a day. Since it is a holiday, we tend to over-indulge, so a serving size of around 8 ounces (227 grams) is likely a good estimate. I use a rule of thumb that two children will eat about the same as one adult. If they are all younger or older you may want to use 3 to 1 or 1½ to 1, respectively.
So 14 adults at 8 ounces each, plus 5 children at 4 ounces each would come out to 132 ounces or 8¼ lbs (3.7 kg). Note that this is the meat portion only.
A whole turkey is about 53% meat by weight. Close enough to say double the weight of meat you want to get the weight of turkey. But before you do that, one more decision. How many leftover servings do you want? For the sake of example, if you have a family of four and want to have enough leftover turkey for three meals with an average serving size of 4 ounces, you will need 3 lbs (1.36 kg) more, giving a total weight for meat only of 11¼ lbs (5.1 kg).
Multiply 11¼ by 2 to get the total weight of the bird you will need gives you 22½ lbs (10.2 kg). If you aren't planning on any leftovers, then just use the 8¼ lbs, double that and get a 16½ lb (7.5 kg) turkey.
To learn more about preparing your turkey dinner, read these articles, too: