The iPad 3 screen size has been a hot topic for conversation. There has been a fountain of mis-information and a geyser of semantic debate. At the core, there are only a few possible outcomes.

One set of numbers has been fairly constant, and that is a screen resolution of 2048 by 1536. That makes sense for many reasons. It doubles the size and quadruples the resolution of the 1024 by 768 resolution screen of the iPad 2. We're talking a 3-megapixel screen. This thing will be huge!

Speaking of size, we can't calculate a screen size until we know the pixel density of the display. There really aren't too many choices. Let's start with what Apple is using today, commonly known as the Retina Display. This is manufactured by LG and is used in the iPhone. It has a pixel density of 326 pixels per inch (ppi). With some basic calculation (shown later), it is easy to calculate the screen size to be 7.85 inches. That would mean a 7 inch iPad, rather than a 10 inch iPad. And remember, Steve said no to a 7-inch screen, once upon a time.

The other display rumor has been a 264 ppi display from Sharp. Once again, simple math gets us to a second alternative, the current 9.7 inch screen size of the current iPad. That's more like it! Apple can build a 10 inch iPad if it changes screen suppliers.

So, let's quickly run through the math, as to not lose anybody. First, by dividing the resolution (in pixels) by the pixel density (ppi), I can get the physical length in inches.

Pixels / PPI = Inches

That will get us the height and width of the screen. Second, we need to tap the genius of Pythagoras to calculate the diagonal screen size.

Width2 + Height2 = Diagonal2

Here's a chart of all the numbers just discussed:

 Resolution (pixels) Screen Resolution (inches) Width Height Density Width Height Diagonal iPad 2 1024 768 132 7.76 5.82 9.70 iPhone 960 600 326 2.94 1.84 3.47 7-inch iPad 2048 1536 326 6.28 4.71 7.85 10-inch iPad 2048 1536 264 7.76 5.82 9.70

If it's a choice of 7 or 10 inch iPad, it's a no brainer, it will be the 10 inch.

But I'm reminded of the last scene of the movie, Trading Places. The question is whether to have lobster or crab cakes for lunch. The answer; can't we have both?