A means for making a simple and economical roll force measurement on rolling mill stands. A strain gage consisting of a half-bridge of vertical and horizontal semiconductor strain elements is cemented to opposing strain sites on a given post of both side frames of a rolling mill stand. These half-bridges are wired into a full-bridge strain gage circuit for each post which is responsive to post strain as a function of roll force, but is not responsive to bending moments in the post. Thermal variations affecting strain gage sensitivity are compensated for by energizing each full-bridge circuit with a separate constant current source. Thermal and mechanical drift affecting strain gage zero are compensated for by automatically nulling amplified strain gage output signals by electronic means during the absence of a workpiece in the rolling mill stand. Roll force signals from individual posts, or their sum, are selectively fed to a utilization device such as a roll force indicator or controller.