Let us first know, what is an ounce? It is a unit of volume. Generally alluded to as oz. One of the particularities of the ounce is that it can have an alternative incentive on whether we are utilizing the US unit system or the UK unit system. There are two ounces - dry ounce and fluid ounce. Now comes to the Gallons, referred to as " gal'' which is the unit of volume just like the ounce. Similarly, a gallon is also divided into US liquid gallon and dry gallon. Though the UK also has its gallons and it is 20% larger than the US gallon.
Now coming to the question, there is 128 fl oz in a full gallon and 64 half an in half a gallon.

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1 gallon ( US, Fluid) = 128 oz ( US , Fluid) .
For better understanding, let us see how much liquid a US gallon contains.
1 US cup = the 8 oz
2 US cup = 16 oz
Thus 4 cups are equal to 32 ounces which form ¼ th of a gallon. Therefore 8 cups are equal to 64 oz. That is the half-gallon. Then 16 ups are exactly equal to the 128 oz which is equal to 1 gallon.
US customary unit conversion :-
1 cup = 8 fluid ounce ( fl oz )
1 pint = 2 cup ( c)
1 quart = 2 pints ( pt)
1 gallon = 4 quarts ( qt)
The formula for calculating the number of ounce in a gallon
8 fl oz / c × 2 c / pt × 2 pt / qt × 4 qt / gallon = 128 fl oz / gallon.






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