For the derivation of the Maxwell Garnett equation we start with an array of polarizable particles. By using the Lorentz local field concept, we obtain the Clausius-Mossotti relation:
Where  is the number of particles per unit volume. By using elementary electrostatics, we get for a spherical inclusion with dielectric constant  and a radius  a polarisability :
If we combine  with the Clausius Mosotti equation, we get:
Where  is the effective dielectric constant of the medium,  of the inclusions;  is the volume fraction of the inclusions.<br />
As the model of Maxwell Garnett is a composition of a matrix medium with inclusions we enhance the equation: