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 5 gallons into fluid ounces we have to multiply 5 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

5 gal → V_{(fl oz)}

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

V_{(fl oz)} = 5 gal × 128 fl oz

V_{(fl oz)} = 640 fl oz

The final result is:

5 gal → 640 fl oz

We conclude that 5 gallons is equivalent to 640 fluid ounces:

5 gallons = 640 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 0.0015625 × 5 gallons.

Another way is saying that 5 gallons is equal to 1 ÷ 0.0015625 fluid ounces.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that five gallons is approximately six hundred forty fluid ounces:

5 gal ≅ 640 fl oz

An alternative is also that one fluid ounce is approximately zero point zero zero two times five gallons.

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