A cylinder is a three-dimensional object that has two identical circular ends with straight parallel sides, like a can of beans or a hot water tank. If you are using a cylindrical object for storage of a product, you can calculate the volume in cubic feet using a simple mathematical equation.
The formula for calculating the volume of a cylinder is V=πr2h, where V is the volume, r is the radius and h is the height.
Measuring in Inches
Measure the length of the cylinder and its diameter, Diameter is the widest measurement across a circle crossing the center.
Sciencing Video Vault
Divide the diameter in half to get the radius. For example: if your diameter is 12 inches, the radius would be 6 inches.
Square the radius by multiplying it against itself. For example: 6 x 6 = 36. Note that whenever you square a measurement, the unit of measurement is always squared too, in this case giving you 36 squared inches.
Multiply the squared radius by pi, which is approximately 3.14. For example: 36 x 3.14 = 113.04 square inches. This number represents the area of the cylinder's circular end. The formula for the area of a circle is: A=πr2 .
Multiply the area of the circle by the cylinder's length to get its volume. For example, if the length of your cylinder is 24 inches, then 24 x 113.04 = 2712.96 cubic inches. Note that since you are multiplying squared inches by inches, the result is now cubic inches. That is, inch2 x inch = inch3.
Divide the square inch volume of the cylinder by 1728 to get the cubic feet of the cylinder. For example: 2712.96 / 1728 = 1.57 cubic feet.
Measuring in Feet
If you are calculating the volume of a large cylinder, you can measure the diameter and length in feet instead of inches. The process is exactly the same except that you don't have to convert cubic inches to cubic feet. For example: if your cylinder is 4 feet in diameter and 8 feet in length, the formula would be:
4 feet divided by 2 = 2 feet x 2 feet x 3.14 = 12.56 square feet x 8 feet = 100.48 cubic feet.