It takes 26 styrofoam cups to fill a barrel. Piled up, they form a heap 26 in (66.1 cm) wide and 6.92 in (17.6 cm) tall, which is about the size of a 5-gallon bucket.

To fill a barrel
about 26 styrofoam cups
20 liters of space
about the size of a 5-gallon bucket
Size and weight estimated by AI from typical values. Sizes and weights are typical for an adult or standard styrofoam cup; real ones vary.