Plan for 1/2 pound of meat per person before the pork is cooked. The pork shoulder will lose about 40% of its weight during the cooking process, and take into account the weight of the bone if you buy bone-in pork shoulder. So if you buy 4 pounds of pork, you'll have about 2 pounds once the cooking is done, which would feed 4-6 people. HOWEVER - it seems like pulled pork keeps dividing into more and more meat the more you shred it! So, really that 4 pounds could feed more like 8-10 people, depending upon how you are serving it. Pulled pork tacos are going to use less meat than pulled pork sandwiches, etc. Err on the high side, and the meat freezes well, so you can just save leftovers for later.