High DPI displays require to scale the UI. Otherwise text becomes very tiny and hard to read. A normal computer display has around 96 DPI.
For example the font size 12pt (= 1em = 100%) is quite commonly used and corresponds to 16px.
On a WUXGA 24" 96 DPI display, this leads to: 1in/96px*16px = 1/6in or with 1in= 25.4mm → 25.4mm/96px*16px = 4,2mm.
On a UHD 24" 188 DPI display, this leads to: 25.4mm/188x*16px = 2,1mm.

To fix this problem, operating systems provides virtual pixels (vx) and scale them properly.
In the above example 1 vx correspond to 4 px (2px horizontal x 2px vertical).
Even though the UHD display has four times as much pixels as the WUXGA display, both display offer the same amount of actual usable working space. This makes sense, because the physical size of both screens is the same.
The difference is, that the high DPI display can use twice as much as pixels, to draw letters and lines. Therefore it looks much sharper, with less aliasing.

This service tries to detect the display size that is currently used to view this website. This might not always work well, due to the limitations of beeing a website and the variety of all the operating systems, virtualization, browsers and devices.

All images are rendered in the resolution of the largest display. They are scaled to fit in your browser window.
You can download these images and set them as desktop wallpaper. Then you can see how your screen content fits. Be careful with the wallpaper fit mode you choose, because they might scale the image.