If you would like to know how many cups are in a 5 gallon jug of water, you can calculate this using the following steps:
4 cups in a quart and 4 quarts in a gallon.
5 gallon jug of water = 5 * 4 quarts = 5 * 4 * 4 cups = 80 cups
Result: There are 80 cups in a 5 gallon jug of water.