The parallel axis theorem states that
the moment of inertia of a rigid body about an axis parallel to the axis passing through its center of mass is equal to the sum of the moment of inertia of the object about the axis passing through the center of mass and product of the mass of the object and the square of the distance between two axes.
From the Parallel Axis Theorem, the moment of inertia of a body about an axis parallel to another axis passing through its center of mass is;
I = I_{cm}+ Md^2
Where, I_{cm} is the moment of inertia about an axis passing through the center of mass, M is the mass of the body and d is the distance of the axis from the center of mass.
The moment of inertia of an object about an axis through its center of mass is the minimum moment of inertia for an axis in that direction in space.