Abstract: A battery-powered device and method for determining the skin type of a living subject is disclosed in which an oil sample carried by a probe is subjected to the impingement of an essentially monochromatic light source of predetermined wavelength. The amount of light passing through the oil sample is detected and an output voltage proportional thereto is produced. This output voltage is amplified, integrated and then drives an LED display which indicates the skin type of the subject. Calibration means and a method for calibrating the device utilizing both an oil-free and oily probe are disclosed. The calibration means include both means for adjusting the bandwidth of the output of the amplifying circuit and gain control means for adjusting the output voltage of the amplifying circuit.