A method and system for determining a heading of a vehicle. The method may include receiving, from a mobile computing device, a request for determining the heading of the vehicle. The method may also include retrieving, at least in response to the request, sensor data generated by a magnetometer of the mobile computing device within one or more first time slots, and obtaining a classifier trained to determine a predicted heading of the vehicle. The method may further include, for the sensor data of each of the one or more first time slots, obtaining a feature vector by extracting features from the sensor data, and determining, based on the obtained feature vector, a predicted heading by inputting the feature vector into the classifier. The method may also include determining the heading of the vehicle based on the obtained one or more predicted headings.