Volume can be calculated by a number of mathematical formulas depending on the shape of the three-dimensional object. Remember, all sides of the object should be measured using the same unit of measurement. For an object with a rectangular prism shape, volume is calculated as "length" times "width" times "height."
For a cube shape having all equal sides, volume is calculated as "side" times "side" times "side" or simply, "side" cubed. A pyramid's volume is calculated as one-third times ("base" times "height"). For a sphere, volume is calculated as four-thirds times "pi" times the sphere's radius to the third power.