See Also: https://wiki.archlinux.org/index.php/Xorg#Setting_DPI_manually
Setting DPI manually Note: While you can set any dpi you like and applications using Qt and GTK will scale accordingly, it's recommended to set it to 96, 120 (25% higher), 144 (50% higher), 168 (75% higher), 192 (100% higher) etc., to reduce scaling artifacts to GUI that use bitmaps. Reducing it below 96 dpi may not reduce size of graphical elements of GUI as typically the lowest dpi the icons are made for is 96.
# The bang exclamation is used for comments in the Xresources file
nano $HOME/.Xresources
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!Xft.dpi: 96
Xft.dpi: 227
Xft.rgba: rgb
Xft.antialias: true Xft.hinting: false Xft.lcdfilter: lcddefault
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nano $HOME/.xinitrc
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# hidpi
export GDK_SCALE=2
export GDK_DPI_SCALE=0.95
export QT_SCREEN_SCALE_FACTORS=0.9
export QT_AUTO_SCREEN_SCALE_FACTOR=2
export QT_SCALE_FACTOR=2
xrandr --dpi 227
# Adjust keyboard typematic delay and rate
xset r rate 270 30
exec i3
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