In this manuscript, a numerical investigation on the temperature gradient of a magnetic refrigerator using different geometric configurations of a parallel plate regenerator is presented. The parallel plate regenerator is made up of gadolinium (Gd) as a magnetocaloric material with rectangular channels. The parallel plate regenerator is modeled and numerically investigated for 3D conjugated fluid convection and conduction heat transfer using Ansys Fluent. Two piston-cylinder displacers drive water as the working fluid through the regenerator loop. The hot and cold end heat exchangers are treated with the e-NTU method. The effect of changing the parallel plate regenerator’s dimensional parameters on temperature span is examined against the utilization factor of 0.1, keeping the regenerator’s porosity constant. The maximum temperature span is predicted by comparing simulated parallel plate magnetic regenerators for two diverse sets of dimensional parameters and surface areas is 36.5 K for magnetic field intensity of 0.8 T.