Theorem of Parallel Axis

According to this theorem, moment of inertia of a rigid body about any axis AB is equal to moment of inertia of the body about another axis KL passing through center of mass C of the body in a direction parallel to AB, plus the product of total mass M of the body and square of the perpendicular distance between the two parallel axes.

If h is the perpendicular distance between the axes AB and KL, then according to the theorem of parallel axes,

$\bbox[15px, #e4e4e4, border: 2px solid #000000]{\boldsymbol {\displaystyle {{I}_{{AB}}}={{I}_{{KL}}}+M{{h}^{2}}}}$