How many fluid ounces equals one gallon?

US gallon

128 U.S. ounces are in one U.S. gallon.

153.7 U.S. oz. in one U.K. gallon

UK gallon

160 oz.(U.K.) = one U.K. gallon

133.2 oz (U.K.) = one U.S. gallon

US Gallon = 3.785 liters

UK Gallon = 4.546 liters

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