The typical serving size for any flavor of ice cream is a half cup. So, if you?re trying to figure out how much ice cream to buy for an event, you?ll want to calculate the number of guests times at least half a cup. A gallon of ice cream holds thirty-two (32) servings. However, most people generously serve and eat more than just a simple half cup of ice cream. You?ll want to stock up a little more to accommodate people?s sweet tooth. It?s always better to have more than not enough.