Add to ORKGAnalytical methods for the calculation of the magnetic field such as the surface charge method offer high accuracy at a reduced calculation time compared to the Finite Element Method. However, for the surface charge model the relative permeability of the permanent magnets is assumed to be equal to air and an error is made in the calculation of the magnetic field strength of the magnet. In this paper the relative permeability is taken into account in order to obtain an exact solution for the magnetic field. The interaction force between two magnets is calculated using the expressions for the magnetic field