<p>Vibration energy harvester has always been a subject of interest of research, highlighting the importance of understanding its behavior and explore their potential applications. Piezoelectric and magnetostrictive harvesters are particularly interesting due to their high-power density extraction capabilities. This paper presents an analytical method for obtaining and comparing important output parameters of a piezoelectric-magnetostrictive energy harvester based on the strain energy approach. This method offers a straightforward and simple enough to compare the impact of different geometric and physical parameters on key outcomes such as power, voltage, and current. The harvester beam consists of a metal base surrounded by piezoelectric and magnetostrictive layers subjected to base excitation. Initially, direct relationships were established to calculate the load and unload natural frequencies. Subsequently, the interface circuit was investigated in three configurations: "separate", "parallel", and "series". The effect of layer thicknesses, resistance values, and also pick-up coil turns was examined, and their optimum values were calculated. Due to the capacitive behavior of the piezoelectric layer and the inductive behavior of the magnetostrictive layer, when combined in an equivalent circuit, leads to specific phenomena such as resonance, which have been thoroughly investigated to maximize energy extraction from the hybrid harvester.</p>