Monthly Archives: February 2012

iPad mini?

Q: Do we need to sand down our fingers to a quarter of their size to operate a 7″ or 8″ iPad, as Steve Jobs suggested in an Earnings Call in 2010?

The iOS Human Interace Guidelines say that some things do not change across all iOS devices, e.g.

The comfortable minimum size of tappable UI elements is 44 x 44 points.

There are two screen sizes on iOS: 480×320 and 1024×768 and they need to stay like that if Apple doesn’t want to break all three bazillion Apps.

Look up the physical display dimensions on the technical drawings on Apple’s site. They change by a millimeter or two across device generations, but they give you a good idea of how big the displays are.

On the iPhone/iPod touch, this translates to a minimum physical tappable size of:

(Display width / Horizontal point dimension) x minimum tappable size
(50mm / 320pt) x 44pt = 6,875mm

On the existing 9.7″ iPad:
(149mm / 768pt) x 44pt = 8,536mm

If one was to shrink the 1024×768 display from 9.7″ to let’s say 7″, the screen would have a portrait width of around 107mm.
(107mm / 768pt) x 44pt = 6,13mm

This would be 11% smaller than on the iPhone, on a device you usually hold at a far greater distance.

And at 8″:
(123mm / 768pt) x 44pt = 7,05mm
The 8″ display would come in at 160ppi, very close to the original iPhone at 163ppi.
This would actually match the physical size on the iPhone, and most apps adhering to the 44x44pt finger would still be operable without any changes.

A: No need to sand down your fingers.