The invention relates to a brake device and a method for operating a brake device, wherein said brake device comprises an actuation device, also a booster device, in particular having an electro-hydraulic drive, a piston cylinder device (main cylinder) in order to supply hydraulic pressure medium to the brake circuits, a valve device for controlling or regulating the supply of the pressure medium and an electronic control or regulating device. According to the invention provision is made for additional pressure medium volume to be supplied in a controlled manner to at least one brake circuit by means of a further piston cylinder device, in particular a double stroke piston and at least one valve controlled by the control or regulating device.