How To Calculate Gallons By Cubic Feet

A cubic foot is the volume of a cube with sides equal to 1 foot. This unit of measurement is used to describe the volume of a container — such as a refrigerator — or the capacity of a container. In 1 cubic foot, there are 7.47 U.S. gallons. Note that UK gallons are slightly different. In this case, a cubic foot would equal 6 UK gallons and about 1.83 pints. Cubic feet can also be used to measure the volume or capacity of a container with dry gallons. A cubic foot also equals 6 dry gallons and about 3.42 dry pints. For the purposes of this article, the U.S. liquid gallon is used.

Step 1

Measure the dimensions of the container. For example, if you had a rectangular container, measure its length, width and depth. If you are measuring the capacity of a round container, determine the number of cubic feet it will hold by multiplying 3.1416 (an approximation of pi) by the square of the radius by the container's depth.

Step 2

Multiply the dimensions by each other to determine the number of cubic feet each container can hold. A rectangular container of the dimensions 2 feet in length by 2 feet in width and 2 feet deep would thus have a volume of 8 cubic feet. A round container with a radius of 3 feet, and a depth of 2 feet would have a volume of about 3.1416 x 9 x 2 = 56.66 cubic feet.

Step 3

Multiply the number of cubic feet by 7.47 gallons to determine the number of gallons each container can hold. In the rectangular container example above with a volume of 8 cubic feet, 8 x 7.47 = 59.76 gallons. The volume in gallons of the round container is 56.66 x 7.47 = 423.25 gallons.