A method and system are provided for calibrating a magnetometer of a mobile device. The method comprises displaying a visual indication of a gestural path on a display of the portable electronic device, monitoring for changes in orientation of the portable electronic device, changing the visual indication in response to the monitored changes in the orientation of the portable electronic device, measuring a magnetic field with the magnetometer, and calibrating the magnetometer in accordance with measurements of the magnetic field acquired at different points along the gestural path.