Abstract: A thickness gauge particularly adapted to measuring flatness of conductive sheets such as a steel workpiece. The tester includes a pair of opposed members translatable toward each other for supporting first and second planar electrical contacts. One of the contacts is disposed to support the workpiece to be gauged, and an electrical circuit is connected to the pair of contacts, to be completed when the contacts are both in contact with the workpiece. Means are provided for maintaining the parallelism of the contacts while relatively displacing them toward each other. Upon completion of the circuit, means are provided for determining the gap between the contacts which is a measure of the thickness and out-of-flatness of the sheet across the measured plane.