Multiply the measurements for the length, width and height of a square or rectangular object to find its volume. For example, a rectangular box that is 12 feet long, 5 feet wide and 10 feet tall has a volume of 600 cubic feet. Volume is always expressed in cubic feet, inches, yards or whatever the unit of measurement for the object may be.
Multiply the square of the radius; the mathematical constant pi, which begins 3.14; and the height of a cylinder to find its volume. For a cylinder with a radius of 5 centimeters and a height of 10 centimeters, the radius measurement of 5 squared is 25. Twenty-five multiplied by 10 is 250, which, when multiplied by π, is 785.398. The cylinder has a volume of 785.398 cubic centimeters.
Increase the radius to the third power and multiply it by 4π/3 to find the volume of a sphere. For example, if the radius of the sphere is 2 cm, then 2 raised to the third power, or 2 multiplied by 2 multiplied by 2, equals 8 cubic centimeters. Eight multiplied by 4π/3 equals 33.5. The volume of the sphere is 33.5 cubic centimeters.
Raise the length of one side to the third power to find the volume of a cube. For example, if the measurement of one of the cube's side is 5 meters, then 5 raised to the third power is 125. The volume of the cube is 125 meters cubed.