Method for calibrating a photodetector (3), the method including the following steps: measuring an afterpulsing probability and/or timing of the photodetector (3) under different operating conditions defined by values of one or more operating parameters, at least one of which is a single-photon property of an optical signal (2) incident on the photodetector (3) when measuring the afterpulsing probability, and recording the measured afterpulsing probability and/or timing in relation to the values of the one or more operating parameters; and photodetector calibrated using this method.