A switching device is controlled by a microprocessor to selectively configure the circuit between a current measurement mode and a calibration mode. When the switch is set to the “on” state, the circuit acts as a normal prior art circuit, with the output Vout being read by the microprocessor to determine the current to the load. However, when the switch is set to the “off” state, a small value resistor (which may be roughly three orders of magnitude greater than Rshunt) connects the inputs of the measuring circuit so that the circuit can generate an output Vout corresponding to the zero load current. By connecting the V+ and V− inputs together with a low resistance resistor, the no-load condition Vdiff=V+−V−≈0 applies. In this state, the no-load offset can be determined by measuring the output voltage of the circuit without turning off the load.