[pooriaazimi]

I actually did the math in my head (Thales) and thought 290 might be just about right, but if you want to be more accurate, use http://bhtooefr.org/displaycalc.htm . The number at bottom-right is the distance "at which individual pixels will no longer be distinguishable", a.k.a Retina.

Retina iPad 3: 2048x1536, 9.7" display, distance: 13", PPI: 263

A contrived Retina Nexus 7: 1700x1130, 7" display, distance: 11.75", PPI: 291 (I adjusted screen resolution so the distance is about 11.5")

I tried to do the math myself, but failed miserably. This article on TUAW has some formulas: http://www.tuaw.com/2012/03/01/retina-display-macs-ipads-and...

[DominikR]

And on what do you base your assumption that a Nexus 7 is held closer than an iPad?

All those numbers presented seem to be tailored to fit your "calculations". (11,75" vs 13" .. how do you come up with that?)

[pooriaazimi]

The 13" inch, I measured (really! with a tape measure - just before posting that comment). And as I said, I based my assumption on myself and how I always use my iPad and when I used a friend's Galaxy tab a while back; We actually talked about it and how you hold it closer than my iPad. Not a lot, bu by an inch or two. So, that's how I "came up" with 11.5" and tailored the resolutions to give me a number close to it... :)