Split-contact magnetoresistors (SCMs) are Hall effect sensors based on the current deflection effect of the magnetic field. We developed a simulation model of Hall sensors, including SCM, in COMSOL Multiphysics considering the transport mechanisms of diffusion and drift.We can simulate devices with a quite arbitrary shape. We use the magnitude of the current density in the deflection direction (on the longitudinal line of symmetry of the device) as a useful guide for the study of the effects of the geometry on the sensitivity to the magnetic field. Other than rectangular shapes, we propose a device with a Venturi-tube shape to increase the sensitivity of magnetoresistors. © 2012 IEEE.