Richard Gaywood Speculates On The Reasoning Behind The iPhone's Screen Size

9 June 2013


A common meme in the Appleverse is that the original iPhone 3.5” screen size was some sort of platonic ideal for one-handed use, as proposed by Dustin Curtis. I think this is bunk, if only because it only works for people with fairly large hands and quite flexible thumb joints, which can only be some small proportion of Apple’s desired target audience for the device. I think it’s much more likely that the way Apple designed the screen was as follows: (1) work out the minimum width that can hold a QWERTY keyboard and still have the keys wide enough to be typeable on (2) multiply width by 1.5, desired screen aspect ratio, to calculate height (3) There is no step three. Look at an iPhone keyboard some time — it’s hard to imagine typing on it if those keys were even just a few pixels narrower.

The decision was probably fuelled by more than just this1, but I reckon the impact of screen size on the keyboard UI must have been carefully accounted for in the design of the final hardware. As Gaywood notes, the iPhone keyboard does feel very tied to that exact size2. The width of the keys (and the spaces between keys) seem to sit at the limits at what is comfortably useable.

Robert Scoble has recently remarked that he expects Apple to allow the text input interface in iOS 7 to be replaced by third-party solutions. I don’t agree. I think Apple sees the keyboard as the crown-jewels of iOS. Letting external developers mess around with something so core to how the phone is used is just not in line with Apple’s style. Cook commented at D11 that they will open up iOS in ways that do not compromise the user experience, but I am confident that custom keyboards fall in the ‘compromising’ category and are not imminent.

1 No doubt, Jobs’ personal aesthetic preferences had a major role.

2 Gaywood’s theory also offers an explanation as to why Apple only changed the vertical height of the iPhones 5’s display, leaving screen width constant.