Gallons to ounces conversion factors are listed below. To find out how many ounces in a gallon, multiply by the conversion factors or use the converter. 1 Gallon [Fluid, US] = 128 Ounces [Fluid, US], 1 Gallon [Dry, US] = 148.94684 Ounces [Fluid, US], 1 Gallon [UK] = 160 Ounces [UK]. There are 128 ounces in a gallon, because from the largest to the smallest units between gallon and fl. oz, there are 4 quarts in a gallon, 2 pints in a quart, 2 cups in a pint and 8 fl. ounces in a cup, that makes 4 * 2 * 2 * 8 = 128 fl. ounces in a gallon.
For example, to find out how many ounces in a gallon and a half, multiply the gallon value by the conversion factor, that makes 1.5 gal * 128 = 192 ounces in a gallon and a half. For US fluid gallons, there are 128 ounces in a gallon, 64 fl. oz in 1/2 gallon, 32 fl. oz in 1/4 gallon, 16 fl. oz in 1/8 gallon, 42.6 fl. oz in 1/3 gallon and 96 fl. oz in 3/4 gallon. For UK gallons, there are 160 ounces in an imperial gallon, 80 fl. oz in 1/2 gallon, 40 fl. oz in 1/4 gallon, 20 fl. oz in 1/8 gallon, 53.3 fl. oz in 1/3 gallon and 120 fl. oz in 3/4 gallon. Gallon is unit of volume in imperial and US customary systems.
