It shouldn't have any problems with 4K? Make sure that you are setting the DPI setting correctly (either when you start X, or I think i3 will use .Xresources).

It shouldn't have any problems with 4K? Make sure that you are setting the DPI setting correctly (either when you start X, or I think i3 will use .Xresources). E.g for my screen I run at 192 DPI, I can't remember where I got that number from.