The invention relates to a method and to a corresponding device for filling at least one seat cushion of a seat with, and emptying same of, a fluid, in which, during a filling or emptying operation, depending on a switching state of an actuating member designed for filling or emptying the at least one seat cushion, a first pressure value determined upstream of a throttle point through which the fluid flows, and a second pressure value determined downstream of the throttle point, are detected, and, depending on the first pressure value and the second pressure value, an estimated value of a mass of fluid supplied to or removed from the at least one seat cushion is determined.