Apple's iPhone media event isn't until next Tuesday, but rumors about what's coming after that are already circulating and they include reports that a 6-inch model is being tested in the Cupertino labs. Of course Apple is testing a 6-inch iPhone model, and they're testing other screen sizes, too, while figuring out whether or not it makes sense to add bigger or smaller screen options. That's called research and design.
According to the Wall Street Journal, Apple is testing screen sizes between 4.8-inches and 6-inches, all of which are bigger than the current iPhone and iPod touch 4-inch display. Insider sources say that right now Apple seems most interested in the 4.8-inch size.
Testing different screen sizes isn't, however, an indication that Apple is set on scaling up the iPhone display. What it really means is that Apple is exploring its options before deciding if a bigger iPhone is a product it really wants to bring to market.
That said, big screen smartphone that approach small tablet sizes are proving popular with consumers. If Apple wants to target that market, they need a bigger iPhone.
A bigger iPhone will come with tradeoffs. The bigger screen size could have a negative impact on battery life, the device will be heavier, and for most people using the bigger model will mean giving up one-handed use -- a feature Apple has used as an iPhone selling point.
If Apple does bump up the screen size, it won't be an arbitrary move. Just as it has done with its jump from a 3.5-inch screen to 4-inches on the iPhone, and its move to Retina Display resolutions, Apple did the math to make sure that apps scale properly and look good on all of its devices, and that will happen with future sizes, too.
Apple already offers three screen sizes outside of its smartphone lineup. The iPod touch uses the same screen size as the iPhone 5, the iPad mini ships with a 7.9-inch display, and the full size iPad screen measures 9.7-inches.
The 3.5-inch display that's on the iPhone 4 and 4S, both of which are still available as the company's discount models will most likely go away when Apple unveils its new iPhones on September 10. The company is expected to introduce the iPhone 5S as its top of the line model with the same 4-inch display used in the iPhone 5, and the mid-range iPhone 5C will use the same screen, too. The iPhone 4 and 4S will go away, bringing an end to Apple's smaller display size and opening the door for alternate screen sizes in the future.
Apple moved away from complicated product lineups when Steve Jobs returned to the company, and that's a philosophy they'll most likely stick with. The iPhone has been available with two screen sizes for some time, just like the iPad, and by dropping the 3.5-inch iPhone models, Apple could make the 4-inch iPhone 5 display its new smaller screen.
As always, Apple isn't offering any hints about what it has in store. With its big media event coming next week, it's a safe bet that the iPhone will drop down to just a single display size, at least for now. No doubt there are bigger models hiding in Apple's labs, but don't expect any of those to ship unless the company decides the products are right and consumers will snap them up.