How Much Blurrier Will a 1080p image look on a 4K Display than on a Native 1080p Display?

[RS13]

So, I prefer to use my TV as a monitor and the one I've been using just died. It seems like all the TVs now a days--or at least the ones you'd want to use as a monitor--run at 4K. The problem is that I don't want to run my games at 4K (fps matter more to me) and I'm worried that they'll be blurry when a 4K TV renders them. Am I off on this? Anyone have any actual experience with it?

[Vagrant0]

4x the pixel density. 1 pixel becomes a block of 4 pixels.

 

Beyond that it matters on the size of the screen, how close you sit to it, and how clearly your own eyes can make out a single pixel. Most of what you would normally see on a 4k TV is actually upscaled from 1080 or 720. The upscaling process typically blends the differences between one pixel and another to make things seem less blocky, but this would not be happening when using a different display resolution on your computer.

[RS13]

That doesn't really help. Keep all that other stuff--screen size, viewing distance, etc.--constant. Are you saying that a 1080p imagine on a 1080p display will look no more blurry than that same image on a 4K TV?

[JimboUK]

The picture will be more "blurry" but how blurry really depends on the scaler in the TV, some are better than others. However one of the biggest problems with 4K TVs is input lag, many have a gaming/PC mode that turns off a lot of features to reduce that lag but it's still there and with some of the features turned off the image quality would suffer.

 

Screen size also matters greatly, the sharpness of the picture depends largely on how many pixels you have per inch, it's why phone screens look so sharp and why 32 inch 1080p monitors look so rough. If you don't want to render at 4K then I would advise against getting a 4K display.