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 be the smallest flagship phone on the market."
    Because UI/UX concerns outweigh c*ck measuring contests. It's not about the biggest screen -- it never was and never will be.
  • Really, you don't think the iPhone's initial success had anything to do with having a larger screen at the time than any of its major competitors? Competitors that had much more capability?
  • Did I inspire this article?
  • Reid vender from WW?
  • Well, I think this is exactly why we got the 4s last year... There's no way they'll compromise the retina display on the iPhone... And I don't want them to... I was in the camp of wanting 4 inch screen, but having a 4s now, I have to say, I really don't care now. I have an iPad, and I like having a pocketable phone. That screen is so good, the 3.5 works just fine.
    Now, a new look, a bit more customization, that would be nice. Would love widgets too, but i know that's not happening.
  • agree with u
  • In my opinion, increasing the screen size without increasing resolution is redundant. You won't actually be able to put more on the screen, it will just be bigger. Might be better for people with larger fingers, but wasn't there some data to suggest that the touch display is easier to use with larger fingers?
  • I dont know but i know a 4+" screen is easier to use then a 3.5
  • I don't think it's redundant -- I really like 4" screens and would appreciate it, even at the cost of reduced pixel density.
  • I hate the pocketability argument. A 4" screen would be no less "pocketable" than the 3.5". The only people who would have trouble are emo kids in their skinny jeans, and they probably have trouble with 3.5" too.
  • What they could do for existing Apps is to just run them 'as-is' at the top of the screen, this leaves a section along the bottom of the screen, maybe enough to display a task switcher without double clicking the home button, or the bottom icon bar, or maybe a notification area.
    Apps could be developed/modified to take account of the extra screen space when the developer can get to it and override the display of what's at the bottom.
  • One other option, or perhaps a less extreme version of pixel-doubling the retina display idea, is to have a 3x screen. Currently, images in apps are stored at the original size (pic.png for 480x320 screens), retina display (pic@2x.png for 960x640 screens), then add a third version (pic@3x.png for 1440x960 screens). This would require less GPU power than the retina display on the new iPad (only about 44% of the pixels to push) and give Apple tons of leeway to change the screen size in the future with a pixel density of 432ppi @ 4" and still call it retina. Then, as non-retina devices become unsupported and apps require the latest version of iOS, the original graphics can be removed to save some space.
  • Thats probably the winner if it's possible from tech side.
  • If they can pixel-double a 480x320 screen they sure can pixel-triple it. The hardware & software capabilities already exist. As far as this theory goes, it's an excellent idea actually.
  • Kudos. I think that could be a fantastic solution. I second that notion!
  • Bravo! This is the best theory so far.
  • Neat idea, I just don't think the yields would be good enough at that density.
  • Sounds good to me. And there's also the possibility that the new iPhone will get a 4.x inch screen (didn't WSJ say "at least" 4 inches?) so the ppi wouldn't be so extreme. But if anybody can source millions of 432ppi displays it's Apple.
    And all that talk about fragmentation and the poor developers: It's still just 3 iPhone resolutions, and 480x320 devices will likely be discontinued by Apple this fall anyway. And the large universal binaries issue can be resolved by Apple on the server-side of things. And developers will adapt like they always do. I hate that notion that progress has to stagnate because of legacy support or incumbents who just wanna keep doing what they were doing and aren't willing to change (e.g. music/tv/movie industry).
  • You're correct in that the WSJ article said "at least 4 inches." So there's definitely a possibility it could be larger. If Apple is planning on putting in a 32nm version of the A5X processor in the next iPhone, it will definitely have the muscle of running a 1920x1280 resolution screen. Wouldn't that be something.
  • Mike, I think you got the issue the wrong way round ;^)
    The issue with increasing the resolution in a new product is not about the development of new apps, it's about rendering the graphics of current versions that are out there.
    For new and updated apps, it doesn't change much for the designers if the new higher res version of the artwork is 1.5x, 2x, 2.67x, 3.33x... they still have to retouch the artwork (re-draw bitmaps or re-rasterize vectors accounting for the increased detail).
    For current apps, only an integer upscaling ratio means no visual differences or artifacts for the users upgrading to the new higher res device.
    For iPhone 3GS users, upgrading to iPhone 4 meant no visual degrade while the apps were upgraded to retina.
    Going 1440x960 in the new iPhone, you'd fulfill this requirement only for old non-retina 480x320 graphics (3x).
    Current 960x640 Retina graphics would be scaled 1.5x, which is blurry.
    So you would've a 432ppi device which is only capable of displaying current apps in a crisp 163ppi, or a blurry 326ppi.
    So for iPhone 4 and 4S users, upgrading would mean no visual change only for their old never-updated-to-retina apps, while for all their retina app library it would mean half the ppi or half the sharpness until update.
    Not much inviting.
  • Frankly speaking, I see no difference in the 4 inch screen and the 4S.
  • Why do they need a 4 inch screen?
    Because a few android devices have it?
    who cares, it's outselling them even with a smaller screen
  • That's a good question. And why 4"? It's like that rumor started and people seemed to jump on it. Why not 4.5"? 5"?
    But I will say that it's not just android. Windows phones and Blackberries will have bigger screens as well. It's one thing to say that someone like Samsung used a larger screen to build marketshare, but you have to look around. Every flagship phone will have a larger screen.
    Reviewers & consumers equate larger screens with higher end. That's just the way it is. Even the mini iPad will be considered low end over the regular ipad. As a result, many won't pay much for a smaller device.
    Apple makes a living on charging premium prices and getting subsidies from carriers. How much longer are consumers willing to shell out and pay premium prices for a smaller phone when EVERY "high end" smartphone has larger and better screen resolutions?
    This isn't something that just snuck up on Apple. They knew this would happen for a long time now. One would think they'd have tackled what they would do about it on a future roadmap even back with Steve Jobs still running things.
  • Windows Phone doesn't have the marketshare to make any relevant impact on Apple, and RIM will likely be gone within two years. It really is just Android for all intents and purposes.
    Apple's MO is that of a leader, not a follower. I don't believe they're likely to start pushing out larger screens just because that happens to be the current trend in Android land.
  • Don't be so arrogant to dismiss Windows. The OS itself is more modern and flat out better than iOS in numerous ways, the 2nd largest phone manufacturer in the world is backing it, and Microsoft products of all sorts continue to dominate the business world. They aren't going away as easily as you assume.
  • You're absolutely right. MS is doing many things right lately and to dismiss the competition, especially one with the capabilities and financial strength of MS, is arrogant & foolish. I give Tim Cook and his senior exec team the benefit of the doubt that they're not that foolish.
  • I've been using Windows Phone exclusively since 2010. I know perfectly well what the good and bad points of the OS are.
    None of those things change the fact that they are not a significant force in the market at this time. Apple has no reason to make any decisions about their next device based on WP7.
  • I really think (and polling that I've seen agrees, as well as average screen size overall) that 4.0" - 4.3" is what a lot of people find closest to ideal. Even accounting for the fact that there are 4.65" flagships like the GNex, a lot of the regular devices like the Rezound, the Droid Razr, etc. max out at 4.3". One handed operation is a thing (and not for pervy reasons :)).
  • This is a good point. The reason for 4" and not larger is for one-handed usability. You can't use a bigger phone than that with one hand comfortably.
  • A trackpad Blackberry still beats any iOS or Andoid phone for one-handed usability and efficiency. Once you learn the keypad shortcuts anyway. Maybe you should try one of those if that is your top concern. It's not like it's impossible to use a 4-4.5" screen one handed for most of the tasks you would ever need to do one handed, it's just not quite as easy for some people.
  • Blackberry doesn't beat anybody in usability
  • Sure they do. I owned them for two years. They are the easiest phones to use one-handed ever made. You barely have to move your thumb.
    Now, they had a lot of other issues with bad hardware and software design, and I don't miss them. But nothing beats them for one handed operation. Point being that ease of one-handed operation isn't the be-all-end-all of phone design, so people should probably stop using that as an excuse.
  • I owned them too. I suppose you could make some argument that they are more one-hand friendly, but with that you actually lose functionality and user-friendlyness. There's a reason BB is floundering and nobody uses trackballs or those crappy little trackpads anymore. Touch screens win hands down for usefullness.
  • It's not just to keep up with all those huge Android phones, there's also the fact that 4g modems are large and quite power hungry -- aside from the marketing angle of measuring screen sizes, a bigger iphone will enable Apple to have a 4g phone with acceptable battery life.
  • Why go with a larger screen. There are two advantages
    - you can see more data OR
    - you can touch things more easily (larger targets)
    Obviously these two are incompatible --- if you choose one, you don't get the other.
    Next why not go with a larger screen?
    - It is certainly possible to use a larger screen on the same size form factor as the current iPhone. There is a lot of bezel that can be removed at the top and the bottom. The mockup showing this looks uglier than it needs to be (IMHO) because they remove too much bezel from the bottom and not enough from the top.
    If you follow this route, all arguments about larger size (and fitting in pockets and so on) become moot.
    If you insist on changing the physical size of the phone
    - complaints that it is too large to fit in various places
    - complaints that typing (especially one-handed) becomes more of a hassle
    There's also a (surprisingly limited) extent to which you can change the aspect ratio of the phone (the phone not the screen) before it starts to look "wrong" and "dumb". Think of things like the Kin. People become accustomed to a device having an aspect ratio and complain when it changes. Apple has done it before (think of 3rd generation iPod nano --- the square one) but we also know that they back-tracked from that decision.
    Putting all this together my analysis is that I disagree with a lot of this article.
    I believe
    - the motivation for a large phone is more pixels, not larger pixels. I am unaware of any serious wave of complaints that the touch targets on iPhone are too small and they should all be grown by about 15% or so.
    - making the screen longer by removing bezel, but keeping the same width in pixels achieves the "I want to see more" goal more sensibly than alternatives.
    For most users it allows longer web pages and more table items, for many apps probably without even a coding change (or a minimal change along the lines of a flag saying "allow views to use larger screen"). For landscape use, it allows 16:9 movies to fit a little better. For old apps, it's easy to fit them in, and the letterboxing is no big deal --- it won't look at all bad, just an extension of the bezel. (If Apple want to be really cute, they could use white letterboxing on white iPhones!) We already have a tradition of letterboxing apps on a different aspect-ratio screen --- look at how 2x iPhone apps fit on an iPad screen.
    So my vote (for reasons of my sense of what people want, what will look good, and what is easiest for developers) is for "Scaling the current iPhone screen to 4-inches, changing the display aspect ratio to something like 9:5"
  • The app "problem" is only a problem because of the way iOS apps are setup/positioned. Apple should focus on making a better layout engine so devs can make responsive layouts, more akin to how Android does it with more of a mix of responsive web design. Do that and app devs will rave with love for Apple. :-D I know I would.
    A larger screen would rock though. The phone could bump itself a bit wider, they just drop all that dead head/footer space and I'd be pleased. :) It's so Mini Me in my hand right now.
  • Still, i watched a tv show i missed over the weekend on my iphone last night. Then read part of a book before going to sleep. In no way was I wishing the screen was a half inch bigger. To be honest, it wouldn't make a significant difference. But it will be significant if i start seeing blurry text again as before on nonretina iphones. Or if apps are all messed up with borders.
  • Dude....seriously let it go. Everyone wants a bigger screen,all you mentioned is better on a bigger screen.
  • And we know your lying cuz iphones cant play flash....
  • Your comment makes no sense -- you don't need flash to watch tv shows.
  • All of these activities are a million times better on my iPad. A bigger screen is a necessity with all the content we consume now.
  • My son (7) does not want to use my iPhone to watch Netflix. He moans if it is on the only device available for him to watch it on. His reason: "It is too small." He wants my Evo 3D [or my wife's Galaxy Nexus], at a minimum, and preferably my iPad (retina) and lastly his XOOM.
    Being "able" to do it is far different from enjoying it. My preference is a larger screen. Yours isn't. Ok.
  • It's not like i won't buy the iphone 5 and i do see your point.
    Gruber thinks it'll be the taller iphone option if they do this at all (and means no hit in PPI). I kind of don't mind that as video will fit better. Otherwise i use it in portrait mode most other times and this will work out well. I read a lot as well on iphone and this would mean less page turning.
  • Expecting the OS to automatically be able to adapt your layout to any screen is the same sort of philosophy as hoping that you can write your app once in Java+Swing and expect it to run everywhere. Yes it kinda sorta works --- but the result always looks like garbage compared to a dedicated app, and likewise compared to dedicated layout.
    Apple aren't going to go there for precisely the same reasons that they won't allow into the app store apps running on a "generic" engine, with a generic UI rather than specifically coded for iPhone.
  • A 4" screen on the current iPhone casing isn't a big screen size jump. Increasing screen resolution on a 4" screen will result in a lot of pinch maneuvers for me to be able to read text that has gotten smaller. Small text is already a problem with the 3.5" screen. Hopefully they do it without increasing the resolution in a way that shrinks everything.
  • It needs to at least jump up to 4.5". 4" just isn't worth the trouble. There is almost no gain in the user experience, iOS is fragmented even more, they've done nothing to satisfy the people who are jealous of the Android screens, and 2 years from now we're having the same discussion.
  • 4.5" is just too big for many people.
  • I dont't know where people got the notion that we use iPad and iPhones at different distances. I use both at exactly the same distance or about 8 inches. For me the iPhone is retina and the new iPad is not.
  • Probably from the experience that most of us have first hand of using them at different distances :). I hold my new iPad further away.
  • iPad at 8 inches? What are you, blind?
  • worse, old.
  • makes sense then
  • Why do you call it iphone 5,1? What does the "5,1" mean?
  • It's a revision number. I'm not sure what the actual numbers are, but it's something like this:
    Original iPhone is 1,1
    3G is 1,2
    3GS is 2,1
    4 is 3,1
    4S is 4,1.
    I believe all the x,1 models (excluding the 3G) are GSM models, with x,2 being CDMA models starting with the iPhone 4. The 3G was considered an incremental update from the original iPhone, gaining only 3G capability and a new shell. The first numbers indicate major revision updates due to hardware upgrades. I may be oversimplifying it but that's my understanding. The new iPhone will be the 6th Generation, but due to the numbering from the original iPhone to the 3G, will have a revision number of 5,1. Presumably this means the Verizon version will be 5,2 and Sprint will be 5,3.
  • There were some great articles on this in the past, especially leading up to the release of the 4S. The most logical idea I could think of at the time is to increase screen size 1.25%, which gives us a 4.375" screen. Pixel density could be increased to 1200x800. Retina density is the same.
    iOS will need to scale up any apps running on the larger screen. If they optimize iOS for this screen resolution, keep the 3:2 aspect ratio, and run everything bigger. Before the naysayers say nay, I'm sure Apple has plenty of brilliant engineers to pull this off seamlessly.
    Bigger is better right???
  • Blah, Blah, Blah! All this whining about having a 4in screen on the next iPhone. People need to relax and accept that Apple will not ( I'm hoping that is) increase the current 3.5in screen that has been working just fine for the past 5 yrs. Personally, I find that all these rumors and explanations on how Apple will change the size of the screen by doing this and that are just pointless!
    Why does Apple need to bump up the screen size just because the so called "competition" is dropping out all these new phones with a 4-5.5in screen display... Also, people need to stop and think for just a minute and realize that those phones or phablets (that's what I'm starting to call them) are useless and have high negative reviews after actually using them for a long period of time. Just cause they sell relatively well don't mean it's a hit amongst everyone! If that was the case, Apple wouldn't have sold over 37.04 million iPhones on JUST their last quarter if people really preferred to have a 4-5.5in screen.
    Personally, I can't wait for the next iPhone to come out just like everyone else. But I'm really tired of these silly rumors and yes I know I have the choice to not read them or even listen to them but it's extremely hard not to when it's practically on every tech site I read! I'm really hoping they stick with their 3.5 display, maybe bump up the resolution and make it an Extreme Retina Display, one can only dream but for everyone's sake I really hope they don't touch the screen size just to say they kept up with Android or Windows phones which they have never done since the release of the iPhone.
  • Anything above 3.5" will require multiple hand use, which is inconvenient in my opinion. If they really need to make a bigger screen to compete, I would go the way of the macbook and have size options: 1) iPhone 3.5", 2) iPhone 4.0", etc.
    Can we get a poll on what size screen people prefer?
  • They already did a poll. It may have been on iMore. I believe 4" won. 4"-4.3" and 3.5" came in second and third, but I don't recall which was which.
  • what you just said is nonsense: I have an HTC HD7 Windows Phone, with a 4.3" screen. I use it most often with one hand, for browsing, playing and even text messaging or chatting. you have no idea what you're talking about.
  • Oh, yeah, well just wait until I haul my 42" retina display Apple television on a handcart complete with DC generator and show you what real screen real estate means. ;)
  • Whats with the 5,1 name ?
    If youre gonna do your cout as follows :
    iPhone : 1
    iPhone 3G : 2
    iPhone 3GS: 3
    iPhone 4 : 4
    iPhone 4s : 5
    Next iphone : iPhone 6
    now if you gonna count it as
    iPhone : 1
    iPhone 3G : 2
    iPhone 3Gs : 2,2
    iPhone 4 : 3
    iPhone 4S : 3,2
    next iPhone : 4,1
    5,1 doesnt add up , cause if 4S is just a part of 4 gen, then 3GS is part of 3G gen :)
  • The isone anti-fragmentation alternate to increase the dimensions, advantageous to both users and programmers.
    Use the dimensions of the original iPad.
  • I meant the pixel dimension... The resolution...
  • Let me start off by saying this: I love this site. I love that you pick and choose which rumors to go with, and that sources are damn near accurate when it's come to the last 2 product releases (iPhone 4S and the "New" iPad). That being said...
    Every time i come on this site, or listen to the podcast I constantly hear the same thing: that the people that want more tweaks or a bigger display or a revamped home screen, are a small, small, small, small fragment of the entire iPhone community. Now, that could be very very true. I know people that love the fact that all icons are cute little pictures and that even a trained monkey could pick the right app it wanted. But, this "small fragment of people" concept never seems to come up when it comes to pixels and this oh so glorious "retina" display. Anyone ever stop to think that the people who wouldn't give up their retina display may be a fragment to?
    I mean honestly think. Apple makes products for the "mainstream." Rene has said numerous times on the show "it's a product my mom could use" which is what apple wants. They want friendly tech that everyone can use. then if the "mainstream" doesn't care about a total revamp of the Home Screen or having widgets, I'm pretty sure if apple took of "retina" the mainstream wouldn't notice, or maybe even care. You know what the main stream pays attention to? Two letters...H...D. That's all that matters If apple slapped on their box "...with an all new HD display, apps, photos and video look gorgeous to the eye..." the mainstream would smile and hand over their money. Pixels, and aspect ratios and all other tech savvy individuals care about, means nothing to the mainstream. The whatever number by whatever number goes over their head. The mainstream hears "HD" they know its "really clear."
    Apple said they wouldn't put video on an iPod. Apple said they weren't interested in doing a phone. And if iMore's tips are correct, the 7inch iPad, that Steve Jobs practically damned to hell, will show up this fall. Cook happily said that customers were loving their current 3.5inch product. They know not hint at the fact they could be working on something better for the near future, it hurst the presents sales. So if the pixels are stretched, if the aspect ratio is stretched, if the "retina" is less...retina-y, apple has figured this all out.
  • The best scenario would be for them to go with a industry standard 1280x720 HD display.
  • Blah, blah, blah to all who say get an iPad if you want a larger screen. NOT everyone can afford or wants a 9.7" tablet to read on. At the same time not everyone wants to read on a 3.5" screen either. Personally reading on a tiny screen sucks and while I like iOS I shouldn't have to spend $500-900 to get a second device.
    The reason other platforms and OEM's are making larger screens is clear users want them, they are doing more than making phone calls on their devices in fact I see people spending more time doing everything other than making a phone call on their mobile device (iPhone, Android, etc.).
    Why should Apple increase the screen size, because 5 years ago 320x480 & 3.5" screens were big, 5 years later 960x640 is nice but 3.5" screens are not.
    I don't think Jobs envisioned a need for a phone beyond 3.5" but users do want it and I guarantee if the next phone comes out 4" or bigger those who bitch about it will be in line to get it so don't kid yourself.
    As for the install base, well the next iPhone will sell what another 100-120 million units over the next year so that means they will have a huge install base for developers to cash in on. Over time the older low res iPhones will drop off and be replaced with the newer ones.
    Who knows if Apple will actually do this or not certainly NO ONE HERE KNOWS for sure.
  • Lets face it the screen is staying 3.5'' there are too many factors that will change causing many develop and consumer problem and as someone said up above Apple most likely examined all of this in 2006/07 and 3.5'' was the winner and always will be if you don't like it get an iPad or wait and see if the so called 'mini iPad' comes out! Apple have sold millions of 3.5" iPhone's and we all keep buying them so no one really cares about screen size, as Siri will tell you "if apple make then yes it's the best!"
  • It's important to keep in mind when Apple decided initially on a 3.5" screen that the smartphone world around them was tiny screens. I think the Palm Treo 700p (or 755p..hard to remember) I was using sported a 320x320 2.5" display. The Centro that came out later in 2007 was even smaller at 2.25" but sharper because it kept the same resolution.
  • The Home button will be put on the side.
  • I would love to see a 4-4.5" inch iPhone. Will I be upset if there isn't one? Absolutely not. Anyone making the argument that the screen should be bigger because it's 2012 is not thinking before they speak. If that's the reasoning what happens in 2015? Will we be using 9" phones because the screens have to increase with the years?
    I personally don't care for a bigger iPhone. I'm happy with the 4S. I've had a Droid X, Droid Inc 2 and a GNex and I can say that the ease of use and comfort of the 4S beats out my previous phones.
  • I gotta say, looking at that top picture, going to a 4" screen with the current aspect ratio doesn't seem like much of an improvement. You don't really get any UI benefits, other than making things bigger. You can't fit another row of apps on the screen, for instance. I think if they go with the same aspect ratio, which I'd prefer, they could go to 4.3 without needing to add too much height or width to the phone, and it would be much more beneficial to the end user and still be "pocketable."
  • Think of how easy it would have been if Apple had encouraged (by supporting in the SDK well) apps that are NOT limited to a certain resolution.
    It is possible to build apps that can handle different resolutions. It is.
    But now Apple is stuck between a rock and a hard place, after being so resolution limited. But 3.5" won't last forever.
  • Yes indeed. They could have the beautiful apps associated with other resolution independent systems like Android, Win7, or Swing rather than the oh-so-ugly apps of iOS.
    Wait, that doesn't sound right...
  • My preference would be a 4" screen at the same DPI - but with a 720p resolution.
  • either way it goes, i cant wait t see it!
  • Rene. I understand your point here, but if you follow that logic, and that apps CONTROL the screen size, then it can NEVER change. And that means iPhone 36 will have the same screen layout as iPhone 1. Really don't see that happening. At some point, Apple will have to make the change. When the iPad first dropped, we had to make due with boxed or scaled up iPhone apps. Then the market caught up. It is no different than having to have 5.1 to run something. If you don't, oh well. Current apps will work in some fashion and the dev's will get started on new ones to fill that new screen.
  • There's another option.
    Currently all apps work in a logical screen size of 320 x 480 points. Assets can be supplied in either 320x480 or 640x960 pixels.
    In iOS 6, Apple could introduce a new, optional, logical screen size of 1200 x 800 points, but continue to support the legacy 320 x 480 size. All current apps would be scaled by the OS by a factor of either 2.5 or 1.5.
    New apps would still need to add a third asset size (default, @2x, and @2.5x) to fully support the new physical screen size, but legacy apps would work just fine (well as fine as a non-retina app works today), and we would get a new 1200x800 4.x" retina display.
  • Typo above: It's 2.25, not 2.5.
  • Typo in the typo fix: From the current logical it is a scale of 2.5. The scale from @2x to a new 1200x800 is 1.25.
  • I really don't want a wider phone. A taller screen would be rather nice, though, particularly if Apple uses some of the currently wasted space, so the phone itself is only slightly taller. I don't mind some letterboxing on older apps. Leaving a sliver of space at the top for notifications would prevent them from overlapping the running app as they do now.
  • While the leap to Retina Displays was pixel-doubling, that's not exactly the constraint that Apple is up against when increasing pixel densities: the real constraint is maintaining whole-number multiples of the original virtual point resolutions.
    So the next leap up in screen densities for iOS (or any) displays isn't 4x, it's 3x.
    Rather than assuming that the next size up would have to be 1920 x 1280, if it ever did happen, it would actually be (3 * 480) x (3 * 320) or 1440 x 960. Or a pixel density of ~435ppi. Not insane, but still waaaay overkill.
    But also very very close to a 1280x720 "standard" and without devs having to change a single thing.
  • I should add, not having to change a thing if we developers stay in UIKit-land and follow all the rules to a T, and/or if in CA/CG-land we've already accounted for device scale without assuming that ">1" == "2" :)
  • I don't think it's required to stick to integer scaling. If the 3GS can't handle the workload it could be orphaned on iOS 5, and the 4/4s have enough horsepower to scale by a non-integer factor.
  • Integer scaling is exactly required. It's nothing to do with whether the GPU can handle it, it's what the on-screen elements look like when they're off pixel-boundaries.
    If Integer scaling weren't required, Apple could just increase the screen size freely to whatever size and resolution they wanted, have current apps run in compatibility mode by scaling to "full screen", and newer apps would "optimize" by taking advantage of the new higher dimensions.
  • Play around a little with a good image editor and some iPhone app screenshots. Scale them to 125%. It's not the end of the world if one pixel out of 960,000 is not exactly as God and the designer intended. If you as a developer disagree, get your damn update out by the time the thing is released.
  • Worth keeping in mind when discussing a 4 inch iPhone: Marc Edward's excellent article on what arbitrary screen scales mean to designers.
    A cautionary tale, to say the least.
  • How about stretching the display by changing the aspect ratio as described above but instead of asking developers to fill up that space it is used as a IOS 6 information center/widget bar. Notifications, weather and stocks, social integration? Quick texting/tweeting links? Maybe it swipes from side to side for multiple bars. But developers have the same screen to work with. Rene was offering his thoughts on ways to interact with other apps and messaging without leaving the current app. Well here you go.
  • I like the idea of two iPhones - one 3.5 inch for all the sheep - and one 4.5 inch for us enthusiasts. Apple won't do it, but it would be cool.
    I also like the "information bar" idea. But who knows. Apple could make the whole front the screen or something crazy.
    To think the new iPhone will have the same screen size and add LTE - and that's it - crazy man. They are going to innovate again, lead the way, and surprise us again.
  • You got it backwards. 3.5" for the enthusiasts. 4" for the sheep.
  • 4 inch display for sure. Display will be made vertically and horizontally bigger. Extra pixels at the top will be taken up by widgets or notification bar. Extra pixels on the left and right will be taken up by overlay home screens. App developers can opt to use up the extra space. For example, Apple will opt to change Safari and Mail to use up the additional space at the top, but may choose to leave the Calendar app alone.
  • Missed one other possibility...
    It will be a 1024x768 screen (XGA or half-iPad) screen, which at 326 Retina DPI would be just wider then present width of the iPhone 4/4S unit as a whole (2.35" versus 2.25"). It will be nearly edge to edge, however, so the whole unit will easily stay under 2.5" wide, perhaps just a tad wider than the 4S. The back will be metal, maybe Liquid Metal, and it will look just like a mini-iPad.
    This lets Apple keep saying it's Retina, that the move to 4" isn't because the present dimensions aren't perfect but to align the two platforms video standards and provide more Springboard real estate (5 icon wide), to allow more elegant scaling of apps between iPhone/iPad devices, to let iPad 1 & 2 apps run natively, and to allow side-by-side iPhone apps on the iPad. And all those benefits only cost .25" in width, it still easily fits in your pocket, and it kills the need for a 7" iPad.
  • Nice article Rene.
    One of the ways you figure out the cost impact of going with a larger screen is to figure out the panelization. When a flat panel display is produced at the factory, its produced at a certain size. There are a number of different sizes defined by their generation. You can find a nice table here:
    It also has some examples of panelization (for larger TV displays) for a given Gen 4 panel in 16:9 and 4:3. But you can do the math yourself.
    Just take a panel of a given size, say 2200mm x 2600mm gen 8, and see how the new iPhone display you're theorizing about will fit. If it fits nicely and there's not a lot of throwaway then you've got a reasonable
    solution. If the new display produces a lot less devices than the previous size, that gives you some idea of the price increase for that display.
    It isn't just a matter of doing the math on the display area increase. You have to look at how many they'll make out of a big panel.
  • Another consideration on screen resolution is whether Apple intends to continue to have compatibility in allowing iPhone only apps to run on the new iPad in 2x mode. Apple may well prefer to discontinue 2x mode and force developers to make iPad optimized apps when targeting tablets. Still, some developers don't like making Universal apps and prefer to make iPhone apps and separate, dedicated HD iPad apps and the 2x mode is useful to avoid annoying customers who don't want to be forced to buy both versions. If Apple does intend to keep the 2x mode then the new iPhone resolution needs to be 1024x768 or smaller.
    One resolution that fits well with the constraints is 1024x640 for a 16:10 aspect ratio on a 4" display. This results in 302 dpi, enough to just claim Retina status. The slightly lower dpi means everything will be slightly larger, which probably isn't a bad thing. There's some concern that a really wide aspect ratio makes phones more difficult to use in landscape orientation, certainly the landscape keyboard on a 9:5 aspect screen seems more unwieldy. As such, 16:10 would be a good compromise between the current 3:2 aspect ratio and wider 16:9 or greater options. With a 1024x640 resolution, running existing iPhone apps won't require blurry scaling and will only require minor pillaring, much less than the 1152x640 9:5 proposal. The small increase in height from 960 pixels to 1024 pixels won't allow an extra row of icons which isn't ideal. It'll probably be just used to space the app icons a little further apart. Apple could couple the introduction of a new screen resolution with a much awaited UI redesign for iOS 6, one that makes best use of screen space in both old and new resolutions.
  • Ritchie seems to be back-peddling from his original prediction of no new increase in screen size or, if anything, a less than 4 inch screen. I wouldn't be suprised, considering early last year's buzz that the screen for the iPhone 5 will be a meager 3.8 inches. Apple may be so devious to market the screen as 4 inches.
    Regardless, the new screen size will, based on history, remain the same size for the next 6 years. If the screen is anything less than 4.5 inches, Apple has really lost touch with the typical consumer who is using their device not so much as a smartphone, but an internet browser.
  • Android fragmentation is not primarily an issue of screen size, its about OS-versions, vendor/operator-specific tweaks and hardware configurations. Actually, developing for multiple screen sizes is really straightforward on Android.
    Backwards compatibility is like an anchor that prevents innovation. Why redesign the iphone if its basicly the same thing with a stretched out screen? To disrupt and lead, Apple needs to make sure the device is on par with how we will use it. And I dont think we will be using it for less purposes than today. The current bottleneck is the screen. I believe Apple knows more about optimal screen size today, than they knew when the original iPhone was released.
    I hope Apple keeps the retina resolution and gives us devs more pixels to play with. Its not hard to write screen agnostic code. Apple has infact prepared for this since the beginning. All code samples are written in a way that encorages devs to write screen agnostic code.
    With that said I think it would be more Applesque to raise the bar for developers rather than compromising with the screen resolution for the sake of backward compatibility.
  • You are treating as a given that the fragmentation involved in moving to a 16:9 ratio is inherently bad. It's not. It has to happen eventually; these phones are heavily used as media consumption devices, and all media is now produced in the 16:9 ratio. Better to bite the bullet sooner rather than later, before even MORE apps are made, and get it out of the way. Besides, any dev worth their salt is going to update their apps, and how many people actually actively use apps that have been abandoned by their devs for years now?
  • This is what I WANT Apple to do: 4.5 inch screen, 1280 x 800 resolution. This would mean 336 ppi, and the same aspect ratio. Old apps could be played windowed, and new apps could be shrunk down to fit the 3.5 inch displays.
    Unfortunately, the chances are next to zero for apple to do that. I have an iPhone 4, and I am craving 4.3"+ display. My friend has a Samsung Galaxy note. I know that it is oversized, but there is still a little bit of jealousy involved.
    I had a look at the HTC One X the other day, and that display is beautiful (much better than the Samsung Galaxy S3 display, by the way, which is rubbish). The ppi is well above satisfactory, even though I own an iPhone 4. It's a little over saturated, but I can manage. The display is also a lot brighter. The display is very important to me, so if Apple does not provide a larger display, I may be doing the thing that I never thought I would do: switch to Android.
  • By the way, 1280 x 800 resolution is 1 1/3 the size of the iPhone 4/4S resolution, or 2 2/3 the size of the 3GS. Not the most practical resolution, but it's almost the same ppi, so a lot of objects (buttons, game sprites, etc.) would probably remain the same resolution anyway, giving more viewing room for viewing information. It seems logical to me.
  • Well, I'm hearing some close guesses on here. Those who defend 16:9 are on the mark. The HD video format is available in multiple standard resolutions, all with the 16:9 aspect ratio in common.
    These are:
    1080p: 16 * 120 x 9 * 120 (1920x1080)
    720p: 16 * 80 x 9 * 80 (1280x720)
    540p: 16 * 60 x 9 * 60 (960x540)
    450p: 16 * 50 x 9 * 50 (800x450)
    So you can see how each HD resolution is based upon a root pixel count (120, 80, 60, and 50).
    Now let's think like Apple. The iPhone 4S supports a letter boxed 540p HD resolution (960x540). The vide will exactly fill the width of the phone display (held in landscape orientation) while letter boxing the video with 50 pixels on top and bottom. You get the HD aspect ratio but it doesn't utilize all of the display real estate.
    So with the iPhone 5, Apple has an opportunity to do better. Apple realizes that the HD's aspect ratio is what's critical, as the video stream can be compressed for whatever HD resolution the display supports. So, why not simply invent a new HD resolution, based upon a root pixel punt of 72 pixels, putting it between 540p and 720p. This HD resolution would be 648p (16 * 72 = 1152 x 9 * 72 = 648) resulting in an 1152x648 display.
    An 1152x648 pixel display, at Apple's current 326 pixel per inch iPhone Retina density wold yield a display that is just 8 pixels wider and therefore would easily fit within an iPhone handset that is the same width as all existing iPhones. The display would be taller by approximately 0.48" (almost exactly the height of one row of icons, plus leading space between rows, on the home screen. An 1152x648 display at 326 pixels per inch would yield a display size of 4.05".
    All of the good discussion in this comments section regarding how a taller display would be reasonably easy to support (lists show more items, video is scaled to the wider 16:9 aspect ratio, the extra 8 pixels in the width can be ignored (content would be centered with 4 non-data pixels on either side, etc.
    So, here is my prediction:
    iPhone 5 will have an 1152x648 resolution 16:9 HD format 4.05" display wrapped in a handset that is 0.48" longer (4.98"), exactly the same width (2.31") and 1.4mm thinner (7.9mm), and of course with 4G