While rumors of a smaller iPad have intensified over the past couple of months despite a pretty clear statement by CEO Steve Jobs that “10-inch screen is minimum necessary“, a new report by AppAdvice now highlights why a 7.85″ screen size is actually not as arbitrary as it might seem. The site has calculated that PPI (points per inch) of a 7.85″ iPad display turns out to be 163 which is exactly the same pixel density as the original iPhone and iPod Touch before the Retina Display.
Detailing from the source:
See, when Apple was designing its first iPhone (circa 2006), company engineers determined through testing that the minimum comfortable size for an interactive element on a touchscreen display is 44 x 44 pixels. Anything smaller would yield erratic results. The pixel density used to arrive at this number, naturally, was that used in the first iPhone — again, 163 PPI. (Note that with the advent of the Retina display, the term “points” is used instead of “pixels.”
However, Apple’s Human Interface Guidelines still call for a direct equivalent based on the original measurement. For example, the new iPhone 4/4S HIG has its interactive minimum set at 44 x 44 points, which is 88 x 88 pixels.) In layman’s terms, all this simply means that no app has tappable input zones smaller than Apple’s approved dimensions.
While none of this confirms whether Apple will ever be introducing a smaller iPad or not, it seems pretty clear that existing iPad apps would run reasonably well without modification on such a device.