A method for determining the depth of a parking space using at least one ultrasonic vehicle sensor. According to the method, the following steps are carried out as the vehicle drives longitudinally past the parking space: a) an ultrasonic wave is emitted, b) echo signals of the emitted ultrasonic wave are collected within a measuring window, c) the dispersion is determined and/or the distribution of the echo signals within that dispersion is determined, d) a depth is defined if the dispersion range of all and/or several echo signals that form a concentration within the distribution lies below a pre-determinable threshold value.