The formula and equation for the area moment of inertia of a hollow or solid cylinder, also known as the polar moment of inertia (second moment of area) of a solid or hollow cylinder, is below. The formula is the same for movement about its axis or about its end or diameter:

, where:

I = Area Moment of Inertia of Cylinder (m^4) (expressed as j or I)

r_{o} = Outer Radius (m)

r_{i} = Inner Radius (hole) (m), is 0 for a solid cylinder.