A small popcorn without butter ranges from 200 calories to 670 calories, depending on the movie theater chain. The serving size of a small popcorn varies between theaters as well as the type of oil used to cook the popcorn.
According to a report from the Center for Science in the Public Interest, Cinemark's popcorn contains 200 calories for an 8-cup serving, the least amount of calories for popcorn tested. A small, unbuttered popcorn from AMC theaters contains 225 calories, and the popcorn from Regal Entertainment Group contains 670 calories. A buttery topping can be added, but it will increase the number of calories per serving.