The standard measurement is 1/4# per person, so one box would feed 4 people. Get 8 boxes and you should be good to go. However, take into consideration what else you're serving and whether the crowd is predominantly Italian. (I'm married into an Italian family and trust me, 1/4# of pasta per person is laughable!) The amount of pasta should be adjusted down if it's only being used as a side dish. If it's the main course and there isn't a lot of substance to the sauce used, such as added meat or seafood, or whether bread and/or salad is served, you may want to increase the amount.
