Among the myriad questions you’ll have to ask yourself (and the internet) once you’ve agreed to host Thanksgiving dinner is a pretty pivotal one: “How big of a turkey should I get?”

Predicting how much meat your guests will gobble down might seem impossible, but there are time-tested ways to come up with an estimate. Read on to find out more.

What Size Turkey Do I Need?

The baseline rule of thumb is that your uncooked turkey should weigh about the same number of pounds as there are adults at your table. In other words, a 6-pound turkey provides enough meat for six people; a 10-pound turkey should satiate 10 people, and so on.

That said, you might want to err on the side of excess to guarantee that your visitors feel comfortable having as many servings as they want (and also to give you the chance to indulge in leftovers). Delish recommends allocating 1.25 pounds for each guest, so an eight-person dinner needs a 10-pound turkey; a 20-pound bird will cover 15 people, and so on.

MarthaStewart.com, on the other hand, advises 1.5 pounds of bird per person. “Smaller birds that weigh less than 12 pounds have a smaller meat-to-bone ratio, so figure two pounds per person,” the site says.

In short, choosing the right-sized turkey isn’t an exact science, and other variables—like the number of kids in attendance, and whether your group is known for taking hearty helpings—can complicate things further. Luckily, Butterball has a turkey size calculator that actually accounts for those two factors. You fill out four boxes—number of adults, number of kids, whether you want leftovers, and whether your guests are big or light eaters—and Butterball will not only tell you how many pounds of turkey you’ll need, but also an estimated amount of stuffing to make.

How Long Does It Take to Defrost a Turkey?

Because the amount of time you’ll need to defrost a frozen, uncooked turkey is based on how big it is, Butterball has a calculator for that, too.

It depends on whether you’re thawing it in the refrigerator or using the cold water method, which involves submerging your bird (in its wrapper) in a bucket of cold water. The latter is much faster: You need about half an hour of defrost time per pound of turkey, whereas the refrigerator requires a full day per 4 pounds of turkey. A 12-pound turkey, for instance, will take roughly three days to thaw in the fridge, but only six hours in cold water. However, since you have to replace the water every 30 minutes, it’s more labor-intensive (and time-consuming) than letting the refrigerator do all the work.

Once you've chosen the ideal bird and decided on a defrosting process, here are some expert tips for cooking it to perfection.