A method for operating a drive train includes supplying a motor voltage to an electric motor by a converter for achieving a torque setpoint value, determining an angular velocity actual value and an angular acceleration actual value from values of the angular position of the rotor, determining the torque setpoint value from a moment of inertia and an angular acceleration setpoint value, which is determined as an actuation variable, determining the moment of inertia as the sum of the moment of inertia of the drive train without a load and the moment of inertia of the load, and determining the moment of inertia of the load from a torque actual value and from the angular acceleration actual value.