Quick Answer. On average, a gallon of ice cream will serve approximately 16 people a 1 cup serving of ice cream and 10 people a 1 1/2 cup serving of ice cream. A scoop of ice cream is about 1/2 cup (4 ounces), and a typical serving is about three scoops, or 1 1/2 cups (12 ounces) of ice cream.