There are 128 fluid ounces in a U.S. gallon. In the United States, the gallon is a standard liquid measurement.
One gallon contains 4 quarts, which is also equivalent to 8 pints or 16 cups of liquid.
Other countries use liters over gallons when it comes to liquid measurement. One liter is roughly the equivalent of 1 quart. Thus, 4 liters are approximately the same as 1 U.S. gallon.
It is important to note that fluid ounces and weight ounces are not the same. Liquid ounce measurement takes into account the volume of the liquid, as opposed to dry ounce measurement, which records the weight.