Abstract: Mechanical pressure gauges may be calibrated for linearity by a method which uses the pressure element's initial and final position at zero and full gauge pressure to determine the setting for span (gain) and starting angle of a segment gear. These are then set when the gauge is assembled to provide a completely calibrated gauge without alternately changing first one then the other of the interrelated span radius and starting angle to adjust linearity of a gauge. A vision system is utilized to perform the steps of precisely measuring the initial and final tip position on a reference plane. This information is used along with the geometry of the four-bar gauge linkage to determine the necessary span radius and starting angle, which is a function of the tip to segment gear pivot point distance. These distances can be individually set on each gauge by conventional mechanical measuring tools within tolerances which will immediately produce an assembled gauge within a desired linearity specification.