When planning a buffet, prepare 6 to 8 ounces of protein per person when serving poultry, meat or fish as the main dish, according to About.com. Offer 4 to 5 ounces of potatoes and vegetables for each guest. Plan on 1 1/2 ounces of salad greens, rice and grains to round out the offerings.
Consider the time of day, guest list, length of the party and the type of food being serve when deciding how much food to put out on a buffet. One portion of dessert per person should be enough. If you want guests to take home leftovers, round up your estimates.