Abstract: A method for calibrating a sensor for measuring turbidity and/or solids content of a medium, wherein the sensor comprises at least one transmitting unit and at least two receiving units. The method comprises the steps of registering at least two measurement signals, which depend on the intensity of light scattered in the medium, wherein the light is sent from the transmitting unit and received by the receiving unit, abstracting the measurement signals to a feature vector, automatic selecting of a calibration model based on the feature vector, wherein the feature vector is transmitted to an earlier trained classifier and the classifier associates the calibration model with the feature vector, and calibrating the sensor with the automatically selected calibration model.