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 640 gallons into fluid ounces we have to multiply 640 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

640 gal → V_{(fl oz)}

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

V_{(fl oz)} = 640 gal × 128 fl oz

V_{(fl oz)} = 81920 fl oz

The final result is:

640 gal → 81920 fl oz

We conclude that 640 gallons is equivalent to 81920 fluid ounces:

640 gallons = 81920 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 1.220703125E-5 × 640 gallons.

Another way is saying that 640 gallons is equal to 1 ÷ 1.220703125E-5 fluid ounces.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that six hundred forty gallons is approximately eighty-one thousand nine hundred twenty fluid ounces:

640 gal ≅ 81920 fl oz

An alternative is also that one fluid ounce is approximately zero times six hundred forty 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