The 4 inch iPhone

If Apple changes to a 4-inch screen in the next iPhone (iPhone 5,1), how could they do it while minimizing impact on users and developers? Assuming everyone wants a bigger screen, how does Apple implement it without breaking existing applications, causing backwards compatibility problems, and otherwise fragmenting the platform and frustrating stakeholders? Let's try to figure that out.

For a while now we've been hearing that Apple hadn't yet decided on the next iPhone design, and that while they were then working off the same 3.5-inch size are previous generations, they were still considering increasing the screen size up to 4-inches (but no more than that).

Earlier today both The Wall Street Journal and Reuters published stories saying Apple was going ahead with a 4-inch iPhone screen, but didn't provide any details as to how a 4 inch screen would be implemented. And those details are arguably even more important than the screen size itself.

That's because change has ramifications. Every choice has a cost. When you're dealing with millimeters and milliamps and megabits-per-second, everything is a compromise.

If Apple has indeed chosen to go with a 4 inch screen, there are only so many choices they can make, compromises they can reach, and ramifications that can be handled, developers, and Apple itself.

Scaling the current iPhone screen up to 4-inches

Apple rumored to increase iPhone screen size to 4-inches

Apple can simply take the current 960x640, 326ppi, 2:3, 3.5-inch display and physically scale it up to 4 inches. The pixel density would drop to 288ppi, which would be substantially less, but would still be more than the new iPad's 264ppi display. (And would still be higher than the new iPad display -- so hold that as close as you hold your iPhone and see how it holds up.)

The result of this type of screen would be bigger text, bigger controls and buttons, bigger touch targets -- in other words, bigger apps. There would be no extra pixels gained, so the amount of information that could be displayed wouldn't change, but the same amount of information would be displayed at a larger, presumably easier to consumer, easier to interact with size. Only at a lower density.

Does that matter?

Apple has invested heavily in the "Retina display" marketing concept. Retina, however, is a function of density over distance -- the further away you hold the screen, the lower the density needed for pixels to effectively disappear. Apple could, even tenuously, argue a bigger screen would be held slightly further away, resulting in little net loss of "Retina-ness". (They did that at the new iPad event, after all).

Put it all together and users get the advantages of a bigger screen, developers get the advantage of keeping a consistent screen resolution target, and Apple gets the advantage of not substantially disturbing or disrupting either of those groups. For these reasons, if Apple does go with the a 4-inch screen, this seems to me to be the most likely path they'll take to get there.

Scaling the current iPhone screen to 4-inches, pixel doubling it (again)

Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display and scale it up to 4 inches, and once again double the pixel count to 1920x1280. That pixel density would explode to 579ppi, which... is frankly insane.

Never mind how expensive that kind of panel would be, or how hard it would be to achieve usable yield rates, it's overkill. It would enjoy the same benefits as a physically larger display, but maintain Retina display -- even for a falcon.

But as Georgia pointed out on the podcast earlier, that panel would also cost battery power to light it up and graphics power to push that many pixels around.

Unless Apple wants to increase screen size substantially beyond 4-inches, and screen, battery, and mobile GPU technology advances while prices fall and yield rates shoot through the roof, this seems extremely unlikely.

Scaling the current iPhone screen to 4-inches, changing the aspect ratio

Could the iPhone 5 have a 4-inch screen while keeping the same 4S footprint?

Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display but change the aspect ratio to something closer to 9:5 and increase the height to 4 inches by adding pixels. The resolution would increase to 1152x640, and the pixel density would remain the same. (It's just adding extra pixels to the top and bottom.)

Timothy Collins brought this up on The Verge and John Gruber of Daring Fireball pointed a giant spotlight on it. iLounge later added to this particular rumor pile.

Since pixel size remains the same, text size would remain the same, control/button size would remain the same, and touch target size would remain the same. Apps that use the built-in interface elements would simply add an extra row of information -- an extra row of icons, an extra row to the table or item to the list. The display would be vertically larger, and more information could be displayed on it. But what about apps that don't use built-in UI elements?

Safari would show more of a page's length, Mail would show an extra message, but games and anything with a highly customized, non-table based interface would have to be pillar-boxed. If developers made new versions that fill the extra space, those versions would be cut off on older iPhones. And if developers made 2 versions of the apps, it would mean more work for them and "fatter" binaries for users to download. (A universal app would go from having iPhone and iPad interface elements, to having old iPhone and new iPhone and iPad interfaces.)

While many things are possible, this doesn't seem like a very Apple-esque solution. It would fragment the iPhone platform for developers in a way Apple has resisted so far, and offer incomplete user benefits (increasing pixel count in only one direction).

More importantly, it would mean either significantly redesigning (or eliminating) the Home button, or lengthening the iPhone casing, or a bit of both. iMore has heard the Home button isn't going anywhere, and parts leaks have suggested it looks pretty much the same, so that leaves a longer iPhone and that... would be awkward. (Even if you remove part of the bezel to make room for it.)

Scaling the current iPhone to 4-inches, increasing the number of pixels

Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display and increase both the width and height to 4 inches by adding pixels. The resolution would increase to 1092x728 (or thereabouts), and the pixel density would remain the same. (It's just adding extra pixels all sides.)

As above, text, control/button, and touch target size would all remain the same, because the pixel density would remain the same. Apps that use the built-in interfaces could also add an extra vertical row of icons or list or row information, and could add extra "white" space in many cases, or vertical columns in some cases, to fill in those extra pixels.

While the user gets more information, unlike the vertical-only extension, splitting the extra pixels both ways means neither have enough room for an extra row or column of icons at the same pixel size. Safari would show a more of a page in both length and width, but Mail might not squeeze in an entire extra message, or that much more message contents. And now games and anything with a highly customized, non-table based interface would have to be completely boxed, the way iPhone apps are on the higher pixel count iPad display, or stretched to fit, which would look horrible.

If developers make new versions that fill the extra space, those versions would be cut off on older iPhones, or scaled down to fit that would likewise look horrible. (As I've discussed previously.)

So even more work for developers, maybe an @1.14x physical size, and still "fatter" binaries for users to download.

Automagic scaling, like some platforms promise with sliding components, is as mythical in design as "write-once-deploy-everywhere" is in programming. Lazy developers or incredibly programmatic app implementations might default to it, but pixel perfect designers are going to want pixel level control over every screen size and density.

That makes this solution just as unlikely as the last. Even if Apple takes the (now) unusual step of canceling previous generation iPhones when the new one launches, and abandoning their current lower price point strategy, there would still be hundreds of millions of 480x320/960x640 iPhones and iPod touches on the market, and developers would want their apps to run on that massive install base.

increase both the width and height to 4 inches by adding pixels. The resolution would increase to 1092x728 (or thereabouts), and the pixel density would remain the same. (It's just adding extra pixels all sides.)

Switching to 720p resolution

Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display and simply swap it out for a standard resolution screen like 1280x720, at 16:9.

There are Android Devices that use this screen, but so far they can't be made any smaller/denser than 4.3 inches (see the HTC Rezound). Does Apple might have the tech muscle to drive that resolution down to 4 inches any time soon?

The pixel count would be able to show more information horizontally and vertically, and it would be a Retina display and then some at 367 ppi. If icons and text stay the same pixel count, then the presentation would be smaller. If the physical size stays the same, pixel count has to increase.

That's what happens when you changing so many parameters at once -- physical size, pixel count, aspect ratio -- it has both the benefits and the problems of everything else already listed above.

A 720p, 16:9 display at 4-inches would both shrink existing app UI elements and touch targets, and require an even larger letter and pillar box.

Apple would need a third new interface size, existing apps would be boxed, and new apps would need to be cropped or scaled on older devices, resulting in a horrible experience and appearance. That makes this option seem the least likely of the bunch.

Switching to original iPad screen

Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display and simply swap it out for a much smaller version of the 1024x768, 4:3 iPad display. This would peg the density at 320 ppi.

Other than it being the same resolution as the original iPad and iPad 2, there's not much different about this option than the 2:3 1092x728 or the 16:9 1280x720. It has the same benefits and drawbacks as both the previous options.

The argument that it would let iPad apps run on the iPhone is problematic, however, as iPad apps have controls/buttons and touch targets designed for a much larger physical size and if you think shaving fingers down for a 7-inch version of the iPad is a challenge, reducing them to the needlepoints necessary for what would essentially be a 4-inch version of the iPad is even more so.

Under the "let iPhones be iPhones" motto, this doesn't seem likely either.

Something else

Apple could have some other way to handle a 4-inch screen, or combination of ways. Point of fact, Apple already knows what they're planning to do (if they're planning to do it), or at least which methods they're testing. That doesn't diminish the mental exercise of trying to divine it before Apple announces it, but it does put it in context.

If Apple goes with a 4-inch screen -- and until Tim Cook or Phil Schiller holds it up on stage, or it somehow leaks conclusively, a 4-inch screen remains an if -- these are just some possibilities.

And all of them have ramifications, opportunity costs, and compromises. Some simply more than others.

Additional resources

Rene Ritchie

Rene Ritchie is one of the most respected Apple analysts in the business, reaching a combined audience of over 40 million readers a month. His YouTube channel, Vector, has over 90 thousand subscribers and 14 million views and his podcasts, including Debug, have been downloaded over 20 million times. He also regularly co-hosts MacBreak Weekly for the TWiT network and co-hosted CES Live! and Talk Mobile. Based in Montreal, Rene is a former director of product marketing, web developer, and graphic designer. He's authored several books and appeared on numerous television and radio segments to discuss Apple and the technology industry. When not working, he likes to cook, grapple, and spend time with his friends and family.

  • For all of the above reasons, this is why I think a 3.75" screen would be more likely for a next generation iPhone. Although I would love a 4" display on an iPhone, it would be terribly uncharacteristic of Apple to plunge the iPhone series into fragmentation with the possible problems it could cause.
  • I don't think Apple would go through all the hassle for 0.25" of extra space.
    The elongated iPhone would be much better if Apple used the same light sensor from the black iPhone. And by retaining the same ppi, they can keep their existing manufacturing structure. The machines can be reprogrammed to cut 4" screens. Last but not least, the new iPhone would be esthetically more pleasing, because of the removal of more non-screen space.
  • Longer screen would only benefit video, and the ability to add more icons to the home screen. Text would be no larger (one of the biggest drawbacks to a small screen) …and photos would suck. >
  • Au contraire, the extra screen space would be wonderful for extra content.
  • The iPhone doesn't need any more vertical pixels, that's what scrolling is for. Any change needs to add horizontal pixels to significantly decrease the need for scrolling, that's the whole point of having a larger display.
  • I agree, this was my guess back in January. 3.75-3.85 range at same resolution. This would hold at or above the 300ppi Apple described as "retina" for the iPhone. Yes, I wouldn't put it past Apple to try to say well the screen is a little bigger, so you have to hold it further away, but I just don't think they would do that because it's still a one-hand handheld device. Plus, at this size the form factor of the phone can stay basically the same as well.
    As for they wouldn't bother for a .25 size increase, why not? It doesn't really cost them anything to cut out a slightly larger screen.
  • Why fragment your platform just for 0.25" of extra screen space?
  • Scaling the screen up to 3.75" without changing the pixel dimensions would not fragment the platform.
  • Any change at all to the pixel density (PPI) would have all the ramifications associated with adding pixels to the display. Apple doubled from 163ppi to 326ppi with the iPhone 4, just like they doubled from 132ppi to 264ppi with the new iPad because it doesn't introduce any issues with touch element size. If Apple is going to make a larger screen, it would be better off adding pixels than lowering PPI, as adding pixels at least has some advantages. Better to leave touch elements the same size AND get more information on screen than to change touch element size and not get more information on screen.
  • Why don't they just take the current resolution of the iPad 2 and original iPad and shrink it down to 4 inches, leaving the iPhone "5" at a pixel density of 320. This would make all iPad 2 apps work on the iPhone
  • While a good idea in theory, it's an iPhone, not an iPad. There are many apps that are specific for one device.
  • Which is called "fragmentation" ironically
  • That wouldn't work. Everything would be way too small, unless you wore a loupe.
  • From all the mock ups shown here I think the bezel would be a problem. Accidental touch is already a problem with my 4S.
  • You may be one of the few that have this problem.
  • I have a feeling Apple went over all this back in 2006/2007; and the 3.5inch screen was the best - so it'll stay that way.
  • Agree. It'll be interesting to see which, if any, of the "new iPhone" rumors turn out to be true. Rumors are far more entertaining after the actual products are released. We get to see who got fooled by Apple counter-intelligence and fake leaks.
  • Just like no iTunes for Windows, no video on the iPod, only web apps on the iPhone, etc. etc.
  • It has been will well-documented that Steve Jobs did not want to make iTunes for Windows. The iPod did not have video capabilities for many years after its original release. The iPhone did not have the ability to run native third-party apps when it was first released.
    So what rumors are you talking about?
  • those are all software issues. not hardware.
  • How about, Apple is in no way interested in making a tablet?
  • Yes, because Apple is obviously a company that makes one decision and then refuses to adapt. /s
  • Remember, when Apple first released the iPhone, the display was massive. The competition was 3" windows mobile phones. When they released it, they probably also decided that 320 x 480 resolution was enough.
  • Nice article.
    Even though the first option is the easiest. I don't think it will be the one they choose to go with.
    Going Retina on the iPhone 4 and then reducing the pixel density on the iPhone 5 (or new iPhone if you like) will blow. And the fact that Samsung will have higher ppi than their iPhone will make T.Cook very sad.
    I say they will add pixels both ways; width and height. Maybe some magic involved, and voilà you have a nice screen. (Not a fanboy btw)
  • well the new iPad is also known in the market for having a retina display, even at a lower density than the iphone 4/4s. while keeping the current number of pixels and stretching the 3.5inches to 4inches, this will SLIGHTLY lower the pixel density of the new iphone, while keeping the same resolution. and it would still be having a higher pixel count than the new ipad. this strategy won't go against the retina display concept, at all!
    i think this is probably the solution for Apple IF they decided to go 4inches on the iPhone.
  • That's a stupid solution then. Good luck explaining the lesser quality screen and how you'll hold it further away and such nonsense.
  • I agree. I don't think Apple will go backwards in screen quality after touting the retina display so much. My vote is to expand length and width by adding pixels.
  • How about 3.85"? Nearly Retina. Nearly 4 inches. And if the bezel shrinks down to near-zero, the overall enclosure could remain exactly the same size as the 4/4S.
  • Like others have said, why change the screen size for just 0.25"?
  • I have a hard time thinking Apple will, just 6-7 months removed from telling their app developers to add a new resolution to iPad apps to turn around and add a fifth resolution to support tech blog and fan boy claims of "everyone wants a 4" phone". Not the Apple way (Jobs or Cook).
    If anything, 3.75", still retina. Like some have suggested above, they aren't going to go backwards.
    Also, there was a reason that when the devices go Retina they double the resolution. It is the only way to cleanly display the old apps without making them look like total poo.
  • Only PARTIAL POO is acceptable!!!
  • Still far less fragmentation than Android. And with the 3GS likely to be discontinued finally, the developers would only need to support it for another year or so if they wanted to. Then they could just require newer hardware for their apps. They can do that right? It's not against the iOS App Store developer agreement?
  • "Apple could take the current 960x640, 326ppi, 2:3, 3.5-inch display and scale it up to 4 inches, and once again double the pixel count to 1920x1280. That pixel density would explode to 579ppi, which... is frankly insane."
    The same things were said when talk or rumors of the ipad going retina was discussed.
    Yet, at this resolution, apple is free to go to any size (for a phone). Why stop at 4"? That would still be the smallest flagship phone on the market. It's not just Samsung. HTC, Nokia, RIM, LG, etc..they're all sporting bigger screens or will be.
    The same problems would exist. "That 4" phone is too small" "I think 4.5" is the 'sweet' spot" "I want a bigger screen"
    Besides, I didn't hear enough to totally dismiss doubling the resolution. Yield rates? Honestly, i have no clue on that. But of course it'd take more battery and graphics. Apple recently went to quad core graphics so that's no big deal. A bigger phone means a bigger battery though.
    I don't think it's much of a stretch to say that Apple couldn't do a 4.5" 1920x1280 phone. It's the kind of overkill that Apple is known for. They may not be much for spec wars but they've always killed it where it matters..the screen. Considering how important the iphone is to their bottom line, this is absolutely the way they should go.
    Regardless, this is the right way for Apple to do it. They should stay the course until it can be done right (if it needs to be done at all) JMO of course..along with jumping to conclusions that 4" is somehow the perfect the size now.
  • "Why stop at 4"? That would still b