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Why a 7.85" Screen for the Rumored 'iPad Mini' Makes Sense
There are clear limits to how close elements can be on the screen before users can't touch accurately. We believe 10-inch screen is minimum necessary.Jobs' dismissal centers around an interface issue that a 10-inch screen is believed to be the minimum necessary to provide a good user interface.
Still, rumors of a smaller iPad have persisted with the latest rumors pinpointing a 7.85" screen for such a device. Apple has reportedly received samples of 1024x768 7.85" screens with rumors of mass production of the device sometime this fall.
AppAdvice digs into this exact screen size and reveals why the 7.85" size is not as arbitrary as it might seem.
The site calculates the points per inch (PPI) of such an imaginary 7.85" 1024x768 display and finds it to be 163 PPI. This is the exact same pixel density as the original iPhone and iPod Touch before the Retina Display. Apple's human interface guidelines for iOS development for both iPad and iPhone outline that the minimum size for tappable user interface elements at 44 x 44 points (0.27 x 0.27 inches on the original iPhone screen).
This 44 x 44 point size recommendation is true for the original iPhone and the original iPad, even though the original iPad was slightly less pixel-dense. (On Retina-enabled displays, the recommendation remains at 44 x 44 points, but with each point represented by 2 pixels)
What this means is that any iPad application that was designed with these guidelines in mind would never drop below Apple's recommended 44 x 44 point (0.27 x 0.27 inches) when displayed on a 7.85" miniaturized iPad. As we noted in our paper mockup of a iPad mini, that the user interface elements seemed perfectly usable on the smaller screen, and this would explain why. iPad apps would run without modification on a 7.85" iPad without any elements dropping below what Apple considers the minimal tappable size.
None of this means that Apple will definitely be producing such a device, but does show the 7.85" size is not an arbitrary decision. Existing iPad apps would run reasonably well without modification on such a device.