Volume is measure in cubic units. The volume of any figure is the number of cubes needed to fill it completely (like blocks in a box). The volume of a cube would be: side times side times side or the length of one side cubed, because each side of the square is the same. A rectangular prism would be: side A x side B x side C. A sphere = (4/3) x pi x radius cubed, An ellipsoid = (4/3) x pi x radius squared x radius cubed, A cylinder = pi x radius squared x height, A cone = (1/3) x pi x radius squared x height, A pyramid = (1/3) x (base area) x height. All units of measure must be the same.