Knowing how to calibrate the compass on the Phantom 4 drone is very important. Also, the compass calibration is the same for both Phantom 4 and Phantom 4 Pro.
You should calibrate the Phantom 4 compass if the DJI GO 4 app or the status indicator on the Phantom 4 prompts you to calibrate.
For example, you would calibrate the Phantom 4 compass if you are flying the quadcopter in a new area. Also, if you feel the the Phantom 4 drone is not flying correctly or is not reacting to your touch as it should, then calibrating the Phantom 4 compass may fix the issues.
This article covers the steps to calibrate the Phantom 4 compass along with information on status indicator lights and what to do if the calibration fails.