A method and device for calibrating a magnetometer device. In an embodiment, the present invention provides a method to automatically calibrate a magnetometer device in the background with only limited movement in each of the three axis (approximately 20 degrees in each direction). A device implementing the present method will never get stuck in a lock-up state. Embodiments of the present invention provide a conservative and accurate magnetometer status indicator that is essential for indoor navigation using inertial sensors. The implemented algorithm is relatively low computationally intensive and is intelligent enough to know when it has the right kind and right amount of magnetic data before it initiates a calibration.