A device estimates an actual trajectory of a vehicle. The device is designed to determine a sequence of measured position values over a corresponding sequence of times by use of a position sensor. The device is further designed to determine a sequence of odometry values on the basis of sensor data from one or more vehicle sensors. The device is also designed to determine, as an estimation of the actual trajectory of the vehicle, a sequence of estimated pose values for the sequence of times and a systematic position offset for the sequence of measured position values so that an optimization criterion is improved, in particular is optimized at least locally.