A method determines a vehicle mass of a self-driving vehicle, wherein an internal force can be exerted on the self-driving vehicle by the automated control of an electronic drive system and/or an electronic braking system. The method includes determining whether a trigger event is present indicating a change in vehicle mass is likely, and activating a learning operating mode in the presence of a trigger event wherein the self-driving vehicle is operated alternately in a first and a second phase. In the first phase, an internal force is exerted on the self-driving vehicle, and in the second phase, an internal force is exerted on the self-driving vehicle. A disturbing force acting in the phases is determined. The vehicle mass is determined depending on the vehicle acceleration and the internal force present in each phase, as well as depending on the determined disturbing force.