A 5-gallon jug holds a maximum of 43,584 American 1-cent pieces, assuming the pennies fit perfectly in the jug with minimal air between them. One estimate is closer to 35,000 pennies when Halo Animal Rescue performed a fundraiser with a jug full of pennies.

The American penny is 0.750 inch in diameter and 0.06 inch thick. The area of the circular money is pi times the radius squared, which is 0.4424 square inch. Multiply the area times the thickness for 0.0265 cubic inch. A 5-gallon jug is 1,155 cubic inches. Divide the volume of gallon jug by the volume of one penny to find the maximum number of pennies in 5 gallons. Statisticians experiment by counting how many pennies fit in a 5-gallon jug and take an average number over many trials.