You can perform calibration from your bike meter/computer or our mobile app. These are exactly the same steps.
In order to perform it, you need to unhook from the pedals, position the arm vertically downwards, so that no external force acts on it. Then select “calibrate” on the device in question. After a few seconds, a success message should be returned. It is recommended to perform calibration after making a few turns of the crank, or driving a short distance.