IMPORTANT: You MUST always execute a G28 before using this command.

SCREWS_TILT_CALCULATE [DIRECTION=CW|CCW] [MAX_DEVIATION=<value>] [HORIZONTAL_MOVE_Z=<value>] [<probe_parameter>=<value>]

Invokes the Klipper native bed screws adjustment tool. It will command the nozzle to different locations (as defined by the [SCREWS_TILT_ADJUST] stanza in printer.cfg) probing the z height and calculate the number of knob turns to adjust the bed level.

When SCREWS_TILT_CALCULATE is used with the MAX_DEVIATION parameter it can be used to test ahead of printing that the bed is level to within the specified maximum deviation. Consider using SCREWS_TILT_CALCULATE with MAX_DEVIATION as part of your printer power up macro, PRINT_START macro in printer, cfg, or slicer machine print start gcode to validate the bed is still level within the given deviation prior to printing. If the bed screws deviate by more than MAX_DEVIATION then Klipper will halt with a warning, telling you how much to adjust each bed screw, and allow you to re-run SCREWS_TILT_CALCULATE to properly level the bed.

Example:

G28
SCREWS_TILT_CALCULATE MAX_DEVIATION=0.02

SCREWS_TILT_CALCULATE makes use of configuration stanza in printer.cfg to define the positions on the bed screw. These positions are measured from the probe position NOT the nozzle position. The z probe which is in the rear left corner of the print head should be over top the bed screw position when measured.

Below is an example for the Neptune 4 (standard)

[screws_tilt_adjust]
screw1_name: rear left screw
screw1: 55,180
screw2_name: rear right screw
screw2: 225,180
screw3_name: front right screw
screw3: 225,10
screw4_name: front left screw
screw4: 55,10
horizontal_move_z: 10
speed: 200
screw_thread: CW-M4 # Use CW for Clockwise and CCW for Counter Clockwise

See the Klipper docs for more.

PrintsLeo3D:Let Klipper level your bed with the built-in tool screws_tilt_adjust
https://www.youtube.com/watch?v=APAbl5PGEh0
Not the best, not well suited for the N4 series, dated.