An electronic device can include an inertial measurement unit (IMU) operative to monitor the movement of the electronic device. The IMU used in the device can be inaccurate due to the manufacturing process used to construct the IMU and to incorporate the IMU in the electronic device. To correct the IMU output, the electronic device in which the IMU is incorporated can be placed in a testing apparatus that moves the device to known orientations. The IMU output at the known orientations can be compared to an expected true IMU output, and correction factors (e.g., sensitivity and offset matrices) can be calculated. The correction factors can be stored in the device, and applied to the IMU output to provide a true output. The testing apparatus can include a fixture placed in a gimbal movable around three axes.