An electronic device and method is disclosed that determines a fold angle and/or opening state of a foldable electronic device using a self-capacitance measurement of an electrode disposed in the foldable electronic device. Using self-capacitance to determine the opening state provides an accurate result and makes efficient use of power of the foldable electronic device. Further, the technique offers flexibility in the implementation, as it can make use of electrodes, sensors, and/or antennas already present in many foldable electronic devices.