Pulled pork is the triple threat: it's very easy to cook, it's quite cheap, and can feed a crowd; In the barbecue world, those factors rarely come together.
Most importantly, pulled pork is also delicious.
As a hard and fast answer to this question, you should expect an Adult to eat 1/3 lb of pulled pork and Children to eat roughly 1/4 lb.
However, if you're the one cooking the pulled pork, you need to be aware of the differences between raw and cooked weight.
When calculating the amount of pork you need, it's best to think in terms of raw weight - which is the weight of the uncooked meat.
A lot of other websites will give you calculations that rarely make sense because they're giving you the amount of pulled pork in terms of the cooked weight.
This distinction is important because pork butt will lose roughly 40-50% of it's weight when cooked.
You also can't really buy prepared/cooked pulled pork, unless you're buying from a caterer. However, if this is you, don't fret, I have a calculator for that too (found below).
If you're like me, you like to know how people come up with the basis for their calculators so here's a quick breakdown of the math.
Since we know that the Boston Butt will lose roughly 40-50%* of it's weight, we can double the amount of raw pork butt we'll need based on the amount of cooked pulled pork they'll eat.
*The reason you should opt to use 50% rather than 40% is because it's a more conservative estimate. The amount of weight loss is highly variable and it's best to over-estimate than underestimate.
So in terms of raw pork:
The calculator above works based on this function:
(# of Adults input by user * 0.66) + (# of Children input by User * 0.5) = Amount of Raw Pork
Pork butt is a fairly cheap cut of meat (typically $1-2 per pound). However, some folks may be ordering cooked pulled pork from a barbecue caterer and simply need to know how much to order based on the number of Adults and Children attending.
Again, this calculator assumes a 50% weight loss:
The calculator above works based on this function:
(# of Adults input by user * 0.33) + (# of Children input by User * 0.25) = Amount of Cooked Pulled Pork
The above calculations are pretty conservative in terms of the amount of meat per person. It basically assumes they'll be eating the pulled pork on a sandwich. Meaning, they're also eating bread and maybe coleslaw.
If they're eating just the pulled pork, they may eat an upwards of 1/2 lbs of just pulled pork.
Another factor to consider is the weight of the blade bone (scapula) found in bone-in pork butts. The above calculator is based on a bone-less pork butt.
Pork butts typically weigh anywhere from 4 to 10 lbs and the blade bone will weigh anywhere from 0.5 to 0.75 lbs.
Another factor is the cut used. This entire article has been based on the Pork butt or Boston butt. However, some folks might consider using the picnic roast instead.
In my opinion, the Boston butt is superior in terms of taste due to the fat marbling. This is an important realization because the picnic is way less forgiving, and can dry out (less marbling/intramuscular fat).
Meaning, if you're cooking several Butts, you don't have to babysit the cook - this is the reason I deem the pork butt the best cut for a beginner to smoke.
There are also differences in taste and texture - the picnic tastes more like ham. You could even equate these differences to white and dark meat on chicken - dark meat being more forward. Pork butt is fairly neutral and takes really well to barbecue and vinegar sauces.
The picnic will typically offer you less yield too. They're almost always sold with the bone-in, sometimes skin on (which needs to be removed), and just like pork butt, will experience moisture loss.