Love iPhones? Like math? More in our Doing the Math series, examining the numbers behind the hardware.
Recent rumors suggest the iPhone 5 might have a four-inch screen, slightly larger than the 3.5-inch screen in the iPhone 4. I was skeptical of this rumor at first, because I thought boosting the screen size would require Apple to increase the overall size of the handset, too. I fiddled with some numbers and determined that while it’s theoretically possible for Apple to put a 4-inch screen in the iPhone 5 while retaining its current 3:2 aspect ratio, it’s unlikely to happen for a few reasons.
If Apple increases the iPhone 5’s screen size to four inches but keeps it at the 3:2 aspect ratio all iPhones have had thus far, the overall dimensions work out to 3.32 x 2.22 inches. But the iPhone 4 handset’s overall width is only 2.31 inches; if Apple wants to keep the iPhone 5 around the same overall size as the iPhone 4, that only leaves 0.045 inches (1 millimeter) on either side of the display. That’s not a whole lot of clearance between the screen’s edge and the edge of the handset itself; in fact, it essentially means the screen would cover the entire width of the front faceplate.
Apple could work around that issue by slightly increasing the iPhone 5’s width, but there’s another problem. If Apple increases the screen size to 4″ but retains the same 960 x 640 pixel dimensions, the PPI (pixels per inch) value drops to about 289 ppi — well below the iPhone 4 Retina Display’s 326 ppi, and just barely at the threshold of a “Retina Display” level of quality. To maintain 326 ppi, the pixel dimensions on a hypothetical 4-inch, 3:2 screen must increase to the neighborhood of 1080 x 720, plus or minus a few pixels.
App developers would then have three sets of resolutions to support for the iPhone instead of two, and scaling from 960 x 640 to 1080 x 720 wouldn’t be anywhere near as simple as the pixel-doubling that got developers by in the early days before they were able to scale apps up from 480 x 320 resolution. Worse, any apps kept at a 960 x 640 resolution and “zoomed” to fill the new pixel dimensions would probably look pretty terrible; instead of doubling the pixels as happened in the early Retina Display era, the scale works out to 1 1/8 “zoom.”
What if Apple didn’t stick with a 3:2 aspect ratio for the iPhone 5’s screen and switched to something different? Read on to find out.
Continue reading The 4-inch iPhone display: Doing the math
The 4-inch iPhone display: Doing the math originally appeared on TUAW on Wed, 16 Feb 2011 12:00:00 EST. Please see our terms for use of feeds.
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