Why? Samsung’s 4.8-inch Galaxy S3 was the bestselling smartphone during third quarter 2012. Barclays estimates shipments of gadgets with displays 5-inches or larger will grow by nearly nine times to 228 million between now and 2018. These devices are wildly popular in Asia-Pacific region but are just starting to make waves in the U.S.

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Now website iMore has an incredibly in-depth look at how Apple (AAPL) might go about creating a larger iPhone—if it wanted to. In this post, author Rene Ritchie puzzles out the various sizes Apple may be experimenting with. Trouble is, even minor changes to the iPhone’s form factor could have mega-repercussions for app developers everywhere.

Take, for example, simply stretching the screen:

At 4 inches, the 1136×640 iPhone 5 has the same pixel density as the iPhone 4 and iPhone 4S, or 326ppi. What happens if you stretch that out close to 5-inches? Interestingly, it goes to 264ppi. That’s the pixel density of the Retina iPad. It’s a density Apple already manufacturers, much like the shrunken iPad mini display was also a density Apple already manufactured, the 163 ppi of the original iPhone, iPhone 3G, and iPhone 3GS.

Impressive. Still, it is worth noting. Apple has been slow to increase the iPhone’s screen size. After all, it took the company five years to go up in size marginally, from 3.5-inches to 4-inches. Design chief Jonathan Ive explained why in a promotional Apple video, saying “By making the screen taller, but not wider, you can see more of your content, but still comfortably use it with one hand.”