how many ounces in a gallon?

best answer
There are 128 ounces in one gallon. This is the same for both US customary units and the British imperial system. The abbreviation for ounce is “oz” and the symbol for gallon is “gal”. To convert from gallons to ounces multiply the number of gallons by 128. For example 2 gallons multiplied by 128 equals 256 ounces.