Datasheet

Run sudo nano /usr/share/X11/xorg.conf.d/20-calibration.conf and copy the 9 numbers into the TransformationMatrix

option so it looks like:

or whatever you got, into there.

You will want to reboot your Pi to verify you're done

Your touchscreen is now super calibrated, hurrah!

Section "InputClass"

Identifier "STMPE Touchscreen Calibration"

MatchProduct "stmpe"

MatchDevicePath "/dev/input/event*"

Driver "libinput"

Option "TransformationMatrix" "-0.000087 1.094214 -0.028826 -1.091711 -0.004364 1.057821 0 0 1"

EndSection