Abstract: A calibration system for automatically and sequentially calibrating a plurality of electrical measuring systems of a gauging machine is provided. Each measuring system is of the type having a gain circuit, a zero circuit and a combination circuit connected to the preamplifier of a transducer and the zero circuit for combining the output signals of the preamplifier and zero circuits to obtain unamplified compensated electrical input signals which are amplified by the gain circuits and indicated on an indicator. Each of the measuring systems produces an electrical measurement in a predetermined range defined by upper and lower bounds equal in magnitude but opposite in polarity. The calibration system includes a plurality of negative voltage references and a plurality of positive voltage references corresponding to the lower and upper bounds, respectively.