J.M. Hirsch, AP Food Editor

Preparing Thanksgiving dinner is enough of a pressure cooker, never mind having to do on-the-fly math to get it right. Here are all the numbers you need to have a safe, worry-free and delicious Turkey Day dinner.

All serving estimates are generous to allow for plenty of seconds and leftovers.

How big?

For turkeys under 16 pounds, estimate 1 pound per serving (this accounts for bone weight). For larger birds, a bit less is fine; they have a higher meat-to-bone ratio. But if your goal is plenty of leftovers, aim for 11⁄2 pounds per person whatever the turkey's size.

•  For 8 people, buy a 12-pound turkey

•  For 10 people, buy a 15-pound turkey

•  For 12 people, buy an 18-pound turkey

•  For 14 people, buy a 20-pound turkey

The big thaw?

The safest way to thaw a frozen turkey is in the refrigerator. You'll need about 24 hours per 4 to 5 pounds of turkey. You also can put the turkey in a sink of cold water. Change the water every 30 minutes, and plan for about 30 minutes per pound.

The brine

Never brine a turkey for more than about 8 to 10 hours. Much longer and the meat will be too salty. Always keep the bird refrigerated during brining. If the turkey is too big, an ice-filled cooler stored outside is fine, too.

THE ROAST

Roasting temperatures vary widely by recipe. Some go at a slow and steady 325 degrees. Others crank the heat to 400 degrees or 425 degrees for the first hour, then drop it down for the rest of the time.

However you roast, use an instant read thermometer inserted at the innermost part of the thigh (without touching bone) to determine when your turkey is done. The meat needs to hit 165 degrees for safe eating, though some people say thigh meat tastes better at 170 degrees.

The following roasting time estimates are based on a stuffed turkey cooked at 325 degrees. Reduce cooking time by 20 to 40 minutes for turkeys that are not stuffed. And remember, a crowded oven cooks more slowly, so plan ahead if your bird needs to share the space.

•  12-pound turkey: 3 to 4 hours at 325 degrees

•  15-pound turkey: 4 to 41⁄2 hours at 325degrees

•  18-pound turkey: 41⁄2 to 5 hours at 325 degrees

•  20-pound turkey: 5 to 6 hours at 325 degrees

The rest

The turkey should never go directly from the oven to the table. Like most meat, it needs to rest at least 20 minutes.

The sides

n Carrots: a 1-pound bag makes 4 to 5 servings

n Cranberry sauce: a 12-ounce package of fresh cranberries makes about 21⁄4 cups of sauce; a 16-ounce can has 6 servings

n Gravy: plan for 1⁄3 cup of gravy per person

n Green beans: 11⁄2 pounds makes 6 to 8 servings

n Mashed potatoes: a 5-pound bag of potatoes makes 10 to 12 servings

n Stuffing: a 14-ounce bag of stuffing makes about 11 servings