Simulink is too small on my high DPI display in Linux

Hello Everyone,

I am currently using MATLAB R2025a on Ubuntu 24.04 LTS with a high resolution display (2560x1900).

When I first launched MATLAB, the interface was very small. I tried running s.matlab.desktop.Zoom.PersonalValue = 150, which successfully scaled the MATLAB UI. However, Simulink remains too small, and adjusting the scaling value had no effect on it. What can I do to scale and fix the simulink ui ?

[Altaïr]

According to the answers linked below, calibrating the system's DPI after adjusting MATLAB's scale factor can help achieve the desired scaling for Simulink:

https://www.mathworks.com/matlabcentral/answers/2178210

https://www.mathworks.com/matlabcentral/answers/1968389

For step-by-step instructions, please refer @Ruchika Parag's answer.

Answer 1

[Ruchika Parag]

Hi @Ege, in MATLAB R2025a on Linux systems with high-resolution displays, setting:

s.matlab.desktop.Zoom.PersonalValue = 150;

successfully adjusts the scaling of the MATLAB desktop interface. However, this setting does not affect the Simulink user interface. Simulink scaling behavior on Linux is influenced by system-level DPI settings and Qt-related environment variables, which may override or bypass MATLAB-specific UI preferences.

To address this, it is recommended to unset any Qt scaling environment variables before launching MATLAB. This can be done by using a wrapper script as shown below:

#!/bin/bash
unset QT_SCREEN_SCALE_FACTORS
unset QT_AUTO_SCREEN_SCALE_FACTOR
unset QT_ENABLE_HIGHDPI_SCALING
xrandr --dpi 144  # Optional: match DPI to desired scale (e.g., 96 * 1.5)
matlab

Save this as a shell script (e.g., launch_matlab.sh), make it executable (chmod +x launch_matlab.sh), and use it to start MATLAB.

Unsetting these environment variables ensures that Simulink does not apply any additional scaling beyond what is controlled by the system DPI and MATLAB’s own settings. If needed, adjust the xrandr --dpi value to align with the intended display scale (for example, 144 DPI for 150% scaling on a system with a 96 DPI baseline).

In summary:

• The Zoom.PersonalValue setting controls MATLAB's desktop UI scale but does not affect Simulink on Linux.
• Simulink scaling is impacted by Qt environment variables.
• Unsetting these variables and optionally adjusting system DPI using xrandr can correct the display scale in Simulink.

This approach helps ensure consistent scaling across the MATLAB environment. Hope this helps!

Answer 2

[Marlon Silas]

I was finally able to work this out on my Ubuntu machine (25.10). The fix proposed by @Ruchika Parag unfortunately did not work for me, which resulted in me experimenting with all sorts of different environment variables for hours on end. The solution I want to highlight is that, as of R2025b, the setting matlab.desktop.Zoom.PersonalValue does set scaling for the normal matlab UI; it does not however do so for simulink. What I discovered is that Simulink does respond to what used to be the setting for scaling which is matlab.desktop.DisplayScaleFactor.PersonalValue. Setting this slightly higher, say to 1.25 or 1.5, might result in Simulink being scaled correctly, too. It did for me.

Though honestly the main issue here is mathworks neglecting to update their software to Qt6, remaining on Qt5 which has been unsupported since 2023.