Font Size is too small in Kubuntu 16.04 with a 4k display. How to enlarge the size of system fonts / symbols?

Question

I have a 4k resolution screen and the display resolution shows: 3840x2160. I do not want to reduce this resolution. Here is the problem:

I see extremely small fonts, I need to touch my nose to the screen to see when:

1. I login for the first time after a fresh install of Kubuntu 16.04
2. Login screen after reboot or logoff
3. I install applications like Skype, Gedit, Matlab (img below)
4. grub loader screen
5. Small icons when looking through the system menu etc. (img below)

Solutions found:

1. Goto K button>System Settings>Font>Force Fonts DPI = 230
2. None yet
3. None Yet
4. Alter the resolution in /etc/default/grub
5. None Yet

Kindly help!

Screenshots:

Small fonts in apps

Small icons

System Specifications: Kubuntu 16.04, Dell Precision 5510 4k touch screen with NVIDIA Quadro M1000M

Answer 1

Maybe this link helps: Is Ubuntu 4K ready?

This german article says that it was running without issues. The author describes that he was changing the scaling factor under the system preferences and that the scaling was set systemwide for all used fonts.

Kubuntu should probably also have a scaling factor in the settings but I don't know where.

Answer 2

I can't add comments on here yet, but the German article is about Ubuntu and Gnome is doing a much better job at scaling its interface via a change to one setting.

Here is what works on Kubuntu

1. Determine your screen DPI (official foc or with a tester). For me it's 282

2. Create a file which tells X what the DPI is

     # sudo nano /etc/X11/Xsession.d/77set_dpi
   

3. Type the following line using your DPI. Mine was 282

     xrandr --dpi 282x282
   

4. Save file

5. Create another file which tells X what the DPI is

     # nano ~/.Xresources
   

6. Type the following line using your DPI. Mine was 282

     Xft.dpi: 282
     Xft.autohint: 0
     Xft.lcdfilter: lcddefault
     Xft.hintstyle: hintslight
     Xft.hinting: 1
     Xft.antialias: 1
     Xft.rgba: rgb
   

7. Save file
8. Open the KDE menu, type display, pick "Display Configuration"
9. Click on "Scale Display"
10. Adjust to your liking. I don't think there is a rule here
11. Reboot
12. Right-click on your task bar -> Panel options -> Panel settings
13. Click and hold the "Height" button, move up until it looks good

(Adapted from https://www.girialam.com/2016/02/kubuntu-and-hidpi-screen/)

I found that 240 worked best with the Precision 5510. 282 is just too big