A method for ascertaining information relating to a mechanically effective power of an active brake booster of a braking system of a vehicle, including: ascertaining a first piece of information relating to an assisting force that is effectuated with the aid of the operated active brake booster, ascertaining a second piece of information relating to a pressure force in a master brake cylinder of the braking system, situated downstream from the active brake booster, the pressure force acting counter to the operated active brake booster, ascertaining a third piece of information relating to a spring force of at least one spring of the active brake booster and/or of the braking system, the spring force acting counter to the operated active brake booster, and establishing the information relating to the mechanically effective power of the active brake booster, taking into consideration the first, second, and third pieces of information.