I always figure 8oz for the sides so the table I use is {.8 x 90=72 divided by 16.= 4.5 pounds...serving size X number of guest (=) divide this by 16 ounces and you will get a good estimate of how many pounds you will need. You also need to estimate what your guest will most likely want to consume and adjust accordingly. So if I am doing potato salad and baked beans I will make roughly the same for both since they are a common known food and well liked, deviled eggs, I will estimate 1 ½ eggs per person and then add 1 more dozen. If you are doing green beans you might also want to consider doing fresh green beans, you can steam them or par-boil till tender with some thick sliced bacon or oven / grill roast them in a aluminum pan with some lemon pepper and butter they will hold up much better that canned green beans, they will tend to turn to a nasty mush after heated and placed in a hotel pan. Like Hamiltont suggested 4-5 gallons of potato salad, 3 gallons of slaw, 3 gallons of baked bean and maybe a couple gallons of green beans will more than likely do the trick and go with the average hamburger roll not the big buns the bigger the bun the more folks will tend to heap meat on to fill the void keep it small so it looks big and tasty and have a mason jar or a little crock pot of warmed BBQ sauce so they can add extra
Hope this helps
RR /Mike
