Fixing size of UI for two different displays

Question

This might be a naive question. I have laptop (Dell XPS 15 Base) which has maximum resolution 3840 x 2160. And I have extended my display with an external LCD Dell UltraSharp 2408WFP which has maximum resolution 1920 x 1200.

So when I try to set both displays to 1920 x 1200, UI of my laptop is way small (text and icons seems to be really small). And its really annoying and tedious to look and work on that screen. And mostly I prefer to work on my extended display.

I am using Windows 8.1 Pro. And wondering if there is any way that I could enlarge all the text, icons and UI such that both looks same to me.

I tried to look up for it online as well, but not quite sure about theoretical side that what exactly the problem here. Any help would be really appreciated.

Answer 1

The 2408WFP is a 16:10 ratio screen with a native dpi of 94.34 ppi (using this calculator https://www.sven.de/dpi/)

To solve your problem (put the things to scale), you have to choose a resolution with similar PPI for your 15" display which is a 16:9 ratio.

Let's try Full HD 1920x1080. The calculator say 146.86 PPI, that's too much.

1600x900 we are still at 122.38 PPI, too much

1280x720 we are at 97.91 PPI, this should make things look the same on both screens.

Answer 2

Microsoft would like to claim that Windows 8.1 does, as seen here. However, multiple users claim that while the DPIs are different it's completely unusable due to the higher resolution screen being so small you can't see anything, or the lower resolution screen is way too big and blurry.

This question seems to be asking roughly the same thing you are, and while the answers there vary, they all seem to say the same thing - that it's not possible. The second answer by /u/oily is the best workaround, showing how you can set the "Disable display scaling on high DPI settings" setting on a per-app basis if you use it on a single screen predominantly.

So to be blunt, no it's not possible to do in a clean fashion. However, this feature is available in Windows 10, as described in this article. Within display settings, you can use the slider to change the scaling of apps on a per-screen basis.