Conversion formula

The conversion factor from cups to gallons is 0.0625, which means that 1 cup is equal to 0.0625 gallons:

1 cup = 0.0625 gal

To convert 638.9 cups into gallons we have to multiply 638.9 by the conversion factor in order to get the volume amount from cups to gallons. We can also form a simple proportion to calculate the result:

1 cup → 0.0625 gal

638.9 cup → V_(gal)

Solve the above proportion to obtain the volume V in gallons:

V_(gal) = 638.9 cup × 0.0625 gal

V_(gal) = 39.93125 gal

The final result is:

638.9 cup → 39.93125 gal

We conclude that 638.9 cups is equivalent to 39.93125 gallons:

638.9 cups = 39.93125 gallons

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 gallon is equal to 0.025043042729692 × 638.9 cups.

Another way is saying that 638.9 cups is equal to 1 ÷ 0.025043042729692 gallons.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that six hundred thirty-eight point nine cups is approximately thirty-nine point nine three one gallons:

638.9 cup ≅ 39.931 gal

An alternative is also that one gallon is approximately zero point zero two five times six hundred thirty-eight point nine cups.

Conversion table

cups to gallons chart

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