A method ascertains a characteristic variable of a clutch installed in a drive train of a vehicle for transmitting a transmission torque between a clutch input and a clutch output. A first electric motor is connected to the clutch input and to an internal combustion engine and can assume generator operation, during which it is driven by the internal combustion engine. A second electric motor is connected to the clutch output. The clutch input can have a first rotational speed and the clutch output can have a second rotational speed. The transmission torque during generator operation is ascertained by activating the clutch to adopt a slipping state and in doing so by setting a predefined rotational speed difference between the first and second rotational speed. The clutch input torque present at the clutch input is then ascertained and the transmission torque is determined depending on the clutch input torque.