Abstract: To measure the opacity of sheet material, such as paper, a beam of light is directed against the material and the intensity of any light passing through the material is sensed and converted to a visual readout. A plurality of opacity measurements are made at different areas on the sheet material and, when a selected number of measurements have been made, a readout of the average value of the measurements is generated. The particular technique enables a large number of opacity measurements to be quickly and conveniently made and averaged, and is considerably less complicated and time consuming than opacity measurements which are conventionally made as a function of contrast ratios.