Conversion formula

The conversion factor from gallons to fluid ounces is 128, which means that 1 gallon is equal to 128 fluid ounces:

1 gal = 128 fl oz

To convert 1 gallon into fluid ounces we have to multiply 1 by the conversion factor in order to get the volume amount from gallons to fluid ounces. We can also form a simple proportion to calculate the result:

1 gal → 128 fl oz

1 gal → V_{(fl oz)}

Solve the above proportion to obtain the volume V in fluid ounces:

V_{(fl oz)} = 1 gal × 128 fl oz

V_{(fl oz)} = 128 fl oz

The final result is:

1 gal → 128 fl oz

We conclude that 1 gallon is equivalent to 128 fluid ounces:

1 gallon = 128 fluid ounces

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 fluid ounce is equal to 0.0078125 × 1 gallon.

Another way is saying that 1 gallon is equal to 1 ÷ 0.0078125 fluid ounces.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that one gallon is approximately one hundred twenty-eight fluid ounces:

1 gal ≅ 128 fl oz

An alternative is also that one fluid ounce is approximately zero point zero zero eight times one gallon.

Conversion table

gallons to fluid ounces chart

For quick reference purposes, below is the conversion table you can use to convert from gallons to fluid ounces