If you're ordering barbecue from a restaurant for your party at home, always remember three to four people per pound of meat. If you're getting ribs, it's two to three people per full rack of ribs. That way if you've got just ribs, you'll have plenty.
If you have pulled pork, chicken, beef brisket or hamburgers and hotdogs with your ribs, then you can cut those ribs down even more and make them go a lot further for your party.
If you're doing bone-in chicken, you can do a quarter of a chicken per person, giving each person two pieces, which is plenty for any barbecue chicken at a party.
Now let's talk about if you're buying meat to cook it at home for your friends and family. Here is a great rule of thumb: if you're doing pulled pork for your guests, you'll at least want eight ounces—half a pound—of raw meat per person. You can also use that same formula if you're doing pulled chicken or brisket. Keep in mind that these are boneless measurements, so if you're thinking of doing a bone in meat, be sure to factor in the weight of the bone.
If you’re only cooking (or smoking) ribs, plan to have a half of a rack per person, unless you're serving it with other items, such as burgers and hotdogs.
These measurements are based on buffet-style catering, but you know your audience. If you have a group of big eaters, you can easily double those quantities to make sure you have enough.