The accelerometer calibration process in Betaflight is straightforward but requires precision. Connect your flight controller to Betaflight Configurator and navigate to the Setup tab. You'll see a 3D model of your drone and a yellow button labeled "Calibrate Accelerometer." Before clicking this button, place your drone on a perfectly level surface. I usually use a kitchen counter or table that I've verified with a bubble level. Any tilt during calibration will bake that error into your accelerometer readings, which affects auto-level modes like Angle and Horizon.
Once your drone is level, click the Calibrate Accelerometer button and don't touch the drone for about three seconds while it samples the sensor data. You'll see a brief progress indicator, and the process completes quickly. The flight controller is essentially recording what "level" means according to the accelerometer's current orientation. After calibration, the 3D model in Betaflight should show your drone sitting flat when it's actually flat on your table.
Here's something important that catches many builders: if you've mounted your flight controller at an angle or rotated it in your frame, you need to set the board alignment angles first in the Configuration tab before calibrating. For example, if your FC is rotated 45 degrees because of your frame design, enter that rotation value, save and reboot, then calibrate the accelerometer. Otherwise your level reference will be wrong.
Regarding compass calibration, most racing and freestyle pilots don't use it at all because we don't fly with GPS modules. The magnetometer or compass is only relevant when you're using GPS-assisted flight modes like Position Hold or Return to Home, which are features for aerial photography or autonomous drones. Racing quads operate purely on rate or acro modes that don't require heading information.
If you do have a GPS module for long-range flying and need compass calibration, that's typically done through a different process involving rotating the drone in specific patterns, and it's often handled in the GPS tab or through CLI commands. However, for standard racing setups running Betaflight 4.x, you're only concerned with the accelerometer. After calibration, test your work by enabling Angle mode on the bench and tilting the drone gently. It should resist and try to level itself, confirming the accelerometer knows which way is up.
