sudo mouse-dpi-tool /dev/input/event20
Mouse ThinkPad X1 Mouse on /dev/input/event20
Move the device 250mm/10in or more along the x-axis.
Pause 3 seconds before movement to reset, Ctrl+C to exit.
Covered distance in device units:     1062 at frequency 14.4Hz 	|^C
Estimated sampling frequency: 14Hz
To calculate resolution, measure physical distance covered
and look up the matching resolution in the table below
      67mm	    2.65in	     400dpi
      44mm	    1.77in	     600dpi
      33mm	    1.33in	     800dpi
      26mm	    1.06in	    1000dpi
      22mm	    0.89in	    1200dpi
      19mm	    0.76in	    1400dpi
      16mm	    0.66in	    1600dpi
      14mm	    0.59in	    1800dpi
      13mm	    0.53in	    2000dpi
      12mm	    0.48in	    2200dpi
      11mm	    0.44in	    2400dpi
If your resolution is not in the list, calculate it with:
	resolution=1062/inches, or
	resolution=1062 * 25.4/mm

Entry for hwdb match (replace XXX with the resolution in DPI):
mouse:bluetooth:v17efp6088:name:ThinkPad X1 Mouse:
 MOUSE_DPI=XXX@14