The frictional coefficient of an arbitrary spheroid of volume  equals
where  is the translational friction coefficient of a sphere of equivalent volume (Stokes' law)
and  is the Perrin translational friction factor
The frictional coefficient is related to the diffusion constant D by the Einstein relation
Hence,  can be measured directly using  analytical ultracentrifugation, or indirectly using various methods to determine the diffusion constant (e.g., NMR and dynamic light scattering).