27" Dell S2721QS 4K UHD 5ms 60Hz IPS Monitor EXPIRED

Quote from mcpoppin : Thanks for the huge knowledge bomb! I found out the S3221QS has 140PPI while the S2721QS has 164PPI through Rtings. I'm assuming this is when it's ran at the native 4K resolution but I actually had to scale down because everything was too tiny for productivity and I know there's no way I could use 4K on a regular basis. Your post made me do some more research into this and I realized it's hard to find anything comparable to the retina display until 5K monitors are more affordable down the road. I was going to spend $525 on the LG 32UN880 but just now found out that it has 139PPI so about the same as the Dell 32 inch except the USB-C convenience + Monitor Stand adds another couple hundred to the price

Just to clarify a nuance that may not have been understood from my post, higher PPI doesn't necessarily result in a clear display. Higher PPI removes pixelation effects so the picture is smoother. But because of the way drawing is mapped to pixels, the closer the PPI is closer to a multiple of 72, the sharper the drawing. So both come into play.

To understand, let us say an app draws a thin line. The thinnest line possible is mapped to 1 pixel width in 72ppi monitor, 2 pixel widths in a 144ppi monitor. Since the pixels are twice as dense in the latter, both would reproduce the same size looking thin line. If the line isn't horizontal or vertical, there would be pixelation which would look bad in the 72ppi monitor and better on a 144ppi monitor. This is how higher resolution monitor looks sharper.

But what if the monitor was 180ppi. The thin line now must be mapped to 2.5 pixels but you cannot light up 2.5 pixels. So the OS uses anti-aliasing with softer colors at the edges over 3 pixels so it visually looks like it is using 2.5 pixels. The anti-aliasing would make it less sharp and so a 144dpi may actually look better. The higher the ppi, less of this anti-aliasing effect which is how Apple gets away with anti-aliasing in their high ppi retina displays.

So the best approach is to get as high a PPI as is available or you can afford but prefer one that is closer to an integral or half integral over some odd multiple between monitors in a similar ppi range which might suggest a slightly lower ppi one in some cases. Alternatively, it means a small bump up in ppi may in some cases make it worse than better.

This would explain why there are some complaints of things not being sharp with some monitors when used with a Mac even if they are high resolution monitors.

You need to get into the 200+ ppi range for the above to become a non issue.