# Eyeballing the iPad 3 retina display

Today, Apple announced the new iPad 3, which has a bunch of new features and improvements over the iPad2. One of the new features is a much higher resolution display: 2048 x 1536 pixels, which they advertise as a “retina” display: ad-speak for pixels so small your eye can’t see them. The display looks smooth and unpixellated.

But is that really the case? I did a little math and found this claim to be true, more or less. But there are some caveats, and they’re interesting.

[By the way: I’ve done the math here in imperial units, and not metric, because that’s the standard the industry uses for pixels and such. Silly, but it’s one of the last holdouts you’ll see used this way.]

iBalling the numbers

First, you should really read my post Resolving the iPhone resolution, where I first dissected the “retina display” claim for when the iPhone 4 came out. My conclusion then was that yes, the iPhone 4 display has pixels so small you can’t see them under normal circumstances. But in that post I did a bit of math to prove it.

What I found was that if you hold a device about a foot away from your face and have normal vision, the pixels need to be smaller than 0.0035 inches in size for them to be unresolved; in other words, pixels at this size or smaller give you a “retina display”. The iPhone 4 has pixels about 0.0031 inches in size, so it wins.

Ah, iSee

The new iPad is reported to be the same size as the iPad 2, with a display of 7.75 x 5.8 inches. But it does have smaller pixels than the old version! Dividing the size of the display by the number of pixels (2048 x 1536) we get a pixel size of 0.0038 inches (or 264 dots per inch, if you prefer).

Uh oh. That’s actually a bit bigger than what your eye can see! So is this truly a “retina display”?

Well, let’s not be too hasty to poo-poo this new tech. For one thing, the iPad display is only resolved if you hold it a foot or closer to your eyes. After a little testing, I found that I tend to hold my own iPad 2 about 15 - 17 inches from my face. From that distance (let’s call it 16 inches), pixels need to be smaller than 0.0047 inches to be unresolved (again, see my old post about how that works and where that number comes from), and the iPad 3’s pixels are certainly smaller than that!

If you do happen to have perfect eyes, under ideal circumstances you’ll probably be able to see the pixellation in the screen, but it won’t be that big a deal, I’d wager – and if you hold the iPad 3 about 18 inches from your face, the pixels are too small to see in any case. So, for the majority of people, the claim of a “retina display” is probably accurate.

I’ll note, though, that the iPad 3 pixels are larger than those for the iPhone 4. But that’s OK; I tend to hold the iPhone a little closer to my eyes than I do the iPad. In either case, I’m unlikely to see the pixels.