A method for ascertaining a torque loss of an electromechanical brake booster of a braking system, including ascertaining when a user of the braking system requests a brake pressure build-up in at least one wheel brake cylinder of the braking system, using the electromechanical brake booster, by actuating a brake actuation element of the braking system; and optionally determining an actual value with regard to the torque loss of the motor of the electromechanical brake booster, taking into account at least one provided sensor variable with regard to a motor torque of a motor of the electromechanical brake booster, a change over time of a rotation speed of the motor of the electromechanical brake booster, and/or a master brake cylinder pressure that is present in a master brake cylinder of the braking system.