The formula for finding the volume of a cylinder is Pi multiplied by radius squared multiplied by height. Pi is 3.14 (rounded), the ratio of any circle's circumference to its diameter. Radius is the length of the line segment stretching from the center of a circle to its perimeter. Height is the measurement from the base of the cylinder to its top.
Imagine a cylinder 20 inches high with a radius of 5 inches. To find the radius squared, multiply that number by itself, so 5 times 5 equals 25. Now multiply Pi by the radius squared: 3.14 times 25 inches equals 78.5 inches. Next, multiply 78.5 by the height (20 inches). The product is 1,570. Therefore, the volume of this cylinder equals 1,570 cubic inches.