Radius of gyration is defined as the distance from the axis of rotation to a point where the total mass of the body is supposed to be concentrated, so that the moment of inertia about the axis may remain the same. Simply, gyration is the distribution of the components of an object.

Radius of gyration or gyradius refers to distribution of the components of an object around an axis. In terms of [mass moment of inertia], it is the perpendicular distance from the axis of rotation to a point mass (of mass, m) that gives an equivalent inertia to the original object(s) (of mass, m). The nature of the object does not affect the concept, which applies equally to a surface, a bulk mass, or an ensemble of points.Mathematically the radius of gyration is the root mean square distance of the object\’s parts from either its center of mass or a given axis, depending on the relevant application.It is actually the perpendicular distance from point mass to the axis of rotation.