A method for ascertaining a state variable of a magnetic actuator at a particular point in time. The method includes a step of reading in and a step of calculating. In the step of reading in, a first sensor value and at least one second sensor value are read in, the first sensor value representing a physical variable identical to that of the second sensor value, and the first sensor value having been detected after the second sensor value. In the step of calculating, the state variable is calculated using the first sensor value and the second sensor value as input variables to at least one approximation function.