KDE fractional scaling on only one monitor

Is it possible to limit the fractional scaling to only one monitor? I have two monitors. One is 1080p the other is 1440p is it possible to usefractional scalling on the 1440p monitor only? If so how do I do it.

Yes, but only in the Wayland session. In the X11 session, scaling is global; on Wayland, scaling is per-screen, and you’ll be able to set the scale for each screen exactly how you like on the Display and Monitor page in System Settings.


Strange, isn’t 't Debian Bookworm supposed to use KDE with wayland by default?? Because I just tried that and it definitely did not work.

To check if you are running Wayland you can look in Systemsettings -> About this System and then check what Graphics Platform says.

If you are not running Wayland you can select Wayland in SDDM after logging out or rebooting.

Thanks for that tip. Apperently the debian 12 live session still runns with X11 by default.

I think “default” is only for new installations (don’t know how the debian actually handles it). If you can’t select Wayland from SDDM you might have to install a few more packages.

Just in cases someone comes across this thread and still desires per screen scaling under X11:

I use multiple monitors scaled differently in X11 by taking scaling control away from KDE and setting the scaling manually with xrandr.

Under System Settings → Startup and Shutdown → Background Services I disable:

  1. KScreen 2 and
  2. GNOME/GTK Settings Synchronisation Service.

Then I use xrandr to set the scales I want:

xrandr --output DP-4 --auto --output DP-0 --auto --scale 1.75x1.75 --right-of DP-4 --mode 1920x1200

I set this at login by including the above in /etc/X11/xinit/xinitrc.d/50-xrandr.sh.

I use the above to run a 4K screen along with a FHD screen by scaling the FHD.

Of course this is not a officially supported KDE configuration, but it’s worked fine for several years. Should anyone want more info, the arch wiki has quite a good write-up about multihead: