A method for operating a hydraulic braking system, which includes at least one actuatable actuator for generating a hydraulic brake pressure using brake fluid. A first leakage loss of the brake fluid in the braking system is ascertained as a function of a volume of a pressure chamber of the actuator at a starting pressure at the beginning of a braking process and the volume of the pressure chamber when the starting pressure is reached at the conclusion of the braking process. A second leakage loss of the braking fluid is continuously calculated while the braking process is carried out. The first leakage loss is compared to the second leakage loss for the plausibility check after a braking process was carried out.