An aerosol-generating system comprising: a liquid storage portion (201, 1201) for holding a liquid aerosol-forming substrate (202, 1202)； a pair of electrodes (320) arranged adjacent to or in the liquid storage portion； a sensor (110) configured to sense the orientation of the liquid storage portion； and a control system (104). The control system is configured to: measure an electrical quantity between the pair of electrodes； receive orientation information from the sensor； and determine the amount of liquid aerosol-forming substrate held in the liquid storage portion based on electrical quantity information measured between the pair of electrodes and the orientation information received from the sensor.
