A calibration system comprising: a Helmholtz device comprising thee pairs of coils defining an inner volume, wherein each of the three pairs of coils is configured to generate a magnetic field that is uniform throughout the inner volume; a mount configured to accept a device that includes a magnetic sensor, wherein at least a portion of the mount is positioned within the inner volume such that the magnetic sensor is positioned at or near a center of the inner volume when the device is positioned on the mount; and a computer system configured to communicate with the Helmholtz device and the magnetic sensor, wherein the computer system is configured to: provide instructions to cause each of the three pairs of coils to generate a magnetic field; receive signals from the magnetic sensor that are based on characteristics of the magnetic fields received at the magnetic sensor; measure, based on the signals received from the magnetic sensor, one or more characteristics of the magnetic sensor; and determine, using a calibration algorithm, one or more calibration correction factors for the magnetic sensor based on the one or more characteristics of the magnetic sensor and the provided instructions.