The Diners

• The usual rule of thumb for turkey buyers is to allow 1 to 1 1/2 pounds of whole, bone-in turkey for every diner. That leaves a generous allowance for waste -- bones, fat, and the loss of weight as the bird cooks -- while still providing an adequate number of portions. How you apply or bend that rule depends on your specific crew of diners. If you're all light eaters, you might shade your purchase toward the 1-pound mark. If leftovers are your favorite part of the holidays or if the guests include your son's football team, you might go as high as 2 pounds per person.

The Bird

• The bird itself represents a further complication. Large turkeys are meatier than small ones, so their bones represent a smaller percentage of their weight. To put it another way, the larger your gathering -- and the larger the corresponding bird -- the smaller allowance per diner you'll need. On the other hand, if you're feeding a relatively small group of four to eight people, you'll need to allow at least 1 1/2 pounds per person and quite possibly more. Err on the side of a larger bird, if necessary, rather than not having enough to go around.