libinput

• List event devices /dev/input/event*

list-devices

libinput list-devices

measure

• Requires libinput-utils

# Get the Kernel specified touchpad size
libinput measure touchpad-size 100x100 # 1x speed

# Multiply the kernel-specified size by a multiplier (1.5x, 0.8x, etc)
libinput measure touchpad-size 127.28x78.72 # 0.8x speed

159.1x98.4mm