The current revolution in the field of electromagnetic vibration energy harvester where it is desired that both wireless sensor nodes and relevant power sources are cost and size optimized. It is also crucial to ensure that during the design/fabrication of the sensors power sources in the energy harvester, the power deliverable to the sensors is maximum while maintaining an optimized size. A much deliberate efforts has been reported on the dependency of the flux density on the nature of the coupling material placed in the spaces between the transduction magnets of an electromagnetic vibration energy harvester. However, limited research is reported on the minimization of the geometrical magnet dimension including the outer coupling steel which prevent flux leakage affects, the flux density and voltage/power harvested in an electromagnetic vibration energy harvester. This paper presented a premium works to realize an electromagnetic transduction mechanism which optimize the overall geometrical size while maximizing the magnetic flux density simultaneously. The approach adopted justifiably verify the flux variation with the magnet dimension/outer couplings on a Finite Element Magnetic Method Software (FEMM). The associated flux density on the permanent magnet (NdFeB N52) separated at different distances were predicted on the FEMM software. The coupling associated with each flux level were obtained and correlated with the geometry of the transduction magnet. The results will be analyzed and discussed. Empirical formula will be predicted and to be used in the future to produce a miniature energy harvester for wireless sensor nodes application.