An electrometer is disclosed. The electrometer has a high gain differential amplifier having a first input, a second input, and an output. The electrometer also has feedback switching circuitry. The electrometer further has a plurality of feedback elements configured to be selectively and cumulatively added in any parallel combination between the output and the first input of the high gain differential amplifier via the feedback switching circuitry. A method of adjusting a measurement range of an electrometer while the electrometer is being used to measure an electrostatic charge is also disclosed. One or more additional feedback elements are selectively added in parallel with one or more existing feedback elements which are coupled between an output and an input of a high gain differential amplifier of the electrometer.