The Cupertino, Calif.-based company is ordering larger displays from its Asian suppliers as it prepares to start production on the handset next month. Analysts believe the new iPhone will launch in the fall.
A 4-inch display in the next-generation iPhone would be the biggest physical change to Apple's smartphone since it originally launched in 2007. The iPhone has always featured a 3.5-inch screen, but Android manufacturers have continued to push the envelope when it comes to the display size of smartphones. Many smartphones now feature 4.3-inch screens, and others like the Samsung Galaxy Nexus and the upcoming Galaxy S3 sport 4.7-inch displays.
Apple doesn't seem interested in increasing the size of the iPhone screen too much and blurring the line between smartphone and tablet. A bump to 4-inches will make the device more formidable at media-related tasks like watching videos and playing games, while still keeping the overall size of the device the same.
A move to a 4-inch screen may be an external change, but it could present problems for developers under the hood. Developers created more than 200,000 apps in Apple's App Store to run on a 3.5-inch retina display. Apps on the new iPhone will have to run with black bars until developers issue updates to avoid pixilation.
Still, while a 4-inch iPhone could be a bit of a headache for developers, it is a decision that will pay dividends for Apple. Increasing the size of the device's display gives owners of the 4S plenty of reason to upgrade, as well as get some Android users who were holding out for a larger screen to make the switch to an iPhone. As long as there are millions of people buying Apple's new handset, developers won't mind working a bit harder to make sure their apps run well on the device.
The difference between 4 and 3.5-inches may seem small, but for Apple, it's very, very big.