1 US Cup = 0.0625 (1/16) US Fluid Gallon
1 US Cup = 0.053710437 US Dry Gallon
1 Metric Cup = 0.055 Imperial Gallon
For example, to calculate how many gallons of water there are in 8 US cups, multiply the cup value by the conversion factor, 8 cups * 1/16 = 1/2 gallon in 8 cups.
Cup is a volume unit and used mostly to measure liquid and dry foods. There is no international standard for cups but mostly US Customary (236.5 ml) and metric cups (250 ml) are used. The abbreviation is "c".
Gallon is an imperial and US Customary volume unit. The imperial gallons are the largest in capacity (4.546 liters). The abbreviation is "gal".