A method for determining the quantity of filling components in a cylinder of an internal combustion engine. The cylinder is connected to an air supply via an inlet valve and to an exhaust gas conduit via an outlet valve. The method includes the steps of obtaining an exhaust gas back pressure at a specified point in time when the outlet valve is opened during a work cycle of the internal combustion engine and calculating the quantity of the filling components at the specified point in time on the basis of the obtained exhaust gas back pressure. A controller is also provided for carrying out the method and a motor vehicle is also provided that includes the controller.