Does Size Really Matter (for Tablet Screens, that is)?

When the iPad first launched in April 2010 (a mere two years ago) life was fairly simple for mobile computing.  You could use a smartphone, with screen sizes typically 3.5″ and, rarely, growing up to 4″ in diagonal.  Or you could choose an iPad, with its 9.7″ diagonal screen.

The only other portable devices of note were eBook readers, which almost universally had 6″ screens, and of course, these were only for reading books, not for other mobile computing tasks.

But since that time, the market has exploded with choices.

Tablet Screen Size Options

Tablets now come in many different screen sizes.  Although the iPad remains unchanged with its 4:3 aspect ratio (or, to put it in terms similar to how other ratios are measured, a 16:12 ratio) screen and a 9.7″ diagonal; almost all other tablets have adopted a 16:9 (or 16:10) aspect ratio ‘widescreen’ and come in a variety of sizes.

A 7″ diagonal screen seems to be most popular, but they can be found in many different sizes, including a few with larger diagonals than the iPad (most notably Microsoft’s new Surface with a 10.6″ 16:9 diagonal).

Google’s new Nexus 7 tablet announcement earlier this week embraced a 7″ screen.

Samsung offers tablets with four different screen sizes – 7″, 7.7″, 8.9″ and 10.1″.

Note that it is difficult to directly compare diagonal measurements of widescreen displays with the diagonal measurement of Apple’s standard screen display.  Due to the different ratio between screen height and width, a 10.1″ diagonal widescreen actually has slightly fewer square inches of display (43.6 sq inches) than Apple’s 9.7″ display (45.1 sq in), while the 10.6″ diagonal has only very slightly more (48.1 sq in) display area.

As well as Samsung’s four different tablet screen sizes, it also has a ‘cross-over’ device that is sort of midway between a phone and a tablet – its Galaxy Note with a 5.3″ display.

eBook readers, as they evolve to more multi-purpose devices, have grown in screen size too (the latest Kindle and Nook devices have 7″ screens).

Phone Screens Have Grown

Screen sizes have massively increased on smartphones, except for the iPhone, which has remained stuck on an increasingly small seeming 3.5″ (and 3:2 or 16:10.7 format) screen.  It was a good screen size when first released, five years ago, but now looks out of date and no longer state of the art.

Some of the most popular phones currently include :

• Samsung Galaxy S III with a 4.8″ screen
• HTC One X with a 4.7″ screen
• Google Galaxy Nexus with a 4.65″ screen
• Nokia Lumia 900 with a 4.3″ screen
• Apple iPhone, all models, with a 3.5″ screen (but widely expected to get a larger screen when the iPhone 5 is announced later this year)

So there is now a continuum of screen sizes from the small iPhone screen up to the large Microsoft Surface screen.  Which is the best size?

Not Just Screen Size – Pixel Count Too

There is more to understanding the overall viewing experience on a screen than just its physical size alone.  Even that can be deceptive – we’ve already pointed out that the diagonal measurement, while convenient, is not good for comparing screens of different aspect ratios – in such cases it is helpful to understand the total screen area as well as its diagonal size.

The other essential consideration is the number of pixels on the screen – both in terms of the absolute count of pixels and also the density of the pixels on the screen.

If a screen has too few pixels on it, it simply doesn’t show enough information, and with the pixels being spread far apart, both pictures and type look ragged and grainy, rather than smooth.

On the other hand, if a screen has ‘too many’ pixels on it, you no longer see any extra improvement of clarity, because your eye can only make out so many different points at any given distance.  There is some debate as to exactly how fine a resolution our eyes have, and of course, it also depends on how far from our eyes we hold a screen – probably closer in the case of a phone and further away in the case of a tablet.

It seems that once you start to exceed perhaps about 250 pixels per inch for a tablet, or 300 pixels per inch for a phone, you start to get into the realm of diminishing returns whereby the extra pixels don’t make any visible improvement in the image you’re seeing.  Regular computer screens, at an even greater distance, start to tail off at about 200 pixels per inch, and most regular computer screens have pixel densities of 100 or fewer pixels per inch.

Some tablets define their pixel per inch density in their specifications, others don’t, but it is easy to calculate.  Simply divide the larger number of pixels by the screen’s length and the smaller number of pixels by the screen’s height – both calculations should return about the same number, and that is your pixels per inch.

For example, the Amazon Kindle Fire has a screen with a resolution of 1024 x 600 pixels, and dimensions of about 6″ x 3.6″.  This calculates to about 168 pixels per inch – in other words, a moderately low resolution screen for a tablet.

The new Google Nexus 7 has about a 216 pixel per inch count, and the latest iPads go all the way up to 264 pixels per inch (the earlier iPads were 132 pixels).

Which is better – a bigger screen with fewer pixels, or a small screen with more pixels?  It really depends on where you are with pixel density.  In very general terms, as long as pixel density remains greater than about 175 pixels per inch, and if all other things are equal, more screen size is better than more pixels.  But if the pixel density is less than this, perhaps the best thing is to first add more pixels to the current screen dimension before then adding more screen size.

You’ll note we said ‘if all other things are equal’.  Alas, they almost never are.  Which brings us to the next point.

Tradeoffs

There are a number of conflicting design parameters to be considered and balanced against each other.  The main considerations that balance against simply increasing and increasing both the screen size and pixel count tend to revolve around portability, weight, cost, and battery life.

The bigger the screen, the more expensive it is, with the cost relating both to square inches of screen and also the count of pixels within the screen.

Bigger screens need more power to be lit up, and screens with more pixels need more graphic processing power to feed images to them – and the more powerful the GPU, the greater the power it consumes, too.  In blunt terms, bigger screens require matching bigger batteries, which of course then add further cost to the unit.

Bigger screens also add extra weight, as does the weight of the necessary increase in battery capacity too.  Weight is more of an issue than some people believe it to be, because much of the time, a person will be viewing their tablet while holding it.  It is amazing how even a seemingly light 1.5 lb unit, when briefly picked up and put down again, quickly becomes onerously heavy when being held for an hour or more to watch a movie or read a book.

And the bigger the screen, the less portable the device becomes.  Phones generally fit in shirt pockets, smaller tablets usually fit in jacket pockets, but larger tablets can’t be carried on one’s person or inside one’s clothing.  They need a separate carry system, which starts to diminish their convenience and ubiquity, while also increasing the chances of either forgetting the tablet when traveling somewhere, or not having it when one needs it.

Most of these factors seem to be arguing for smaller rather than larger screen sizes.  But what about the user’s requirements – how big a screen do we actually ‘need’?

User Screen Size Requirements

One of the ‘problems’ with the amazingly successful acceptance of tablets is that there is no clearly defined ‘killer app’ for the devices.  There is no primary end purpose driving their design or screen size.  Instead, we all use them for vaguely similar purposes, with each purpose having a varying impact on screen size requirements.

If we are reading and sending email, we don’t need an unusually large screen size at all.  Similarly, if we are reading a book, we can again do this perfectly well on the smallest of tablet screens, and many people have reported happily reading entire books on their phone screen too.  If you’re listening to music, you don’t even need a screen at all, apart from working through the menus to find the music you want.

But if we’re watching a video, then bigger is always better.  Indeed, with much video now being ‘high definition’ (a very elastic term) and usually in a format with either 720 or 1080 pixels in the vertical direction, it is helpful to have a screen with at least that number of pixels in the vertical (smaller) dimension.

The 720p HD specification is 1280×720, and the 1080 (i or p) specification is 1920 x 1080, so if you are wanting to watch this type of video, it is best to have a pixel count of these sizes (or larger).

In terms of screen size in inches for watching video, there’s really no upper or lower limit, although if one matches the pixels required to show a complete HD image to perhaps a 250 pixel per inch density, this would suggest a ‘perfect’ size for 720p video would be about a 5.9″ diagonal screen (or possibly somewhat larger), and for the 1080 video, it would be an 8.8″ diagonal screen (or, again, somewhat larger).

If you’re browsing websites, you want to have enough pixels on your screen so the web pages can fit on your screen without formatting problems.  These days most webpages are designed for a screen width of at least 800 pixels, and an increasing number now call for 1000 or more pixels of width.

It has been common for tablets to address that need by simply rotating them 90 degrees so their wide side becomes the horizontal side.  But this means you don’t see much of the ‘height’ of a web page.  It would be better if the tablet was able to display 1000 or more pixels on its narrow side, something very few tablets can currently do (notable exception being the iPad (2048 x 1536).

So full ‘normal’ web browsing remains a challenge on all tablets.  It is getting better, with increases in both pixel counts and screen size, but is still far from optimal.

If you’re looking at pictures, then you want to have as many pixels and as many square inches as possible.  On the other hand, for much of our pre-digital lives, the printed pictures we’d get when we sent in our rolls of film for processing would be no larger than 4″ x 6″ (ie a 7.75″ diagonal), so it could be argued that as long as the pixel density is high, something like a 7″ sized screen is sufficient for viewing pictures.

If you are playing games, you want a ‘reasonable’ sized screen, but also a sufficiently light device to comfortably hold and control.

Now, put all these factors together to decide how much screen size you really need, and how much you’re willing to trade off in terms of size/weight/cost/battery life to get the screen size you believe you need.

It is difficult, isn’t it.  To give the classic reply to the question about if size really matters, the traditional answer is ‘it isn’t the size, it is how you use it that counts’.  This seems to be as true of tablets as it is, ahem, of other things.

Is Apple’s Obdurate 9.7″ Only Screen Size Policy About to Change?

Steve Jobs used to vociferously declare that he’d never consider an iPad with a smaller sized screen.  He claimed that a significant part of the success of the iPad was due to their getting the screen size compromise exactly right.

The proliferation of smaller tablets that appeared in response to the iPad was due to two reasons – first, the initial inability of Android to support sufficiently high pixel resolutions to sensibly allow for larger screen sizes, and secondly, the inability of other companies to match Apple’s engineering brilliance and come up with a similar sized device that would also be comparable in weight, battery life and cost.

But these limiting factors have disappeared over time, and no longer constrain the ability of competitors to offer similar or even larger sized tablet screens.

The fact remains, however, that most of the tablet ‘action’, other than for the iPad itself, continues to be centered around smaller screen sizes and lower prices (the two being of course very inseparably linked).  This was hinted at with the Amazon Kindle Fire (7″ screen and $199 price) and the Kindle Fire has been more successful (in terms of numbers sold) than any other non-Apple tablet – at least up to this point and the release of the Google Nexus 7.

Google’s new Nexus 7 (also 7″ screen and $199 price, but with more features than the Kindle Fire) shows that manufacturers are clearly angling for this part of the potential tablet market, with $199 in particular thought to be a key compelling number to encourage new buyers to purchase tablets.

Whereas the 1.5 lb iPad with its 9.7″ display starts off at $499 (and quickly goes up in price from there if you wish to add GPS, cell phone data service, or extra storage), smaller 7″ tablets weighing about half as much, and costing less than half the price of the iPad seem to massively extend the market for tablets as a whole.

We predict a huge success for Google’s Nexus 7 tablet as a result.

Apple claims that the market for their larger, heavier, and much more expensive tablets is not being harmed by a new market opening up for smaller, lighter and cheaper devices.  But it doesn’t really matter, at all, if this is true or not.  Either which way, the clear fact is that there is another market opportunity, for these smaller/cheaper tablets, that measures tens of millions of units a year.  Maybe some of the people who buy the smaller tablets would have bought an iPad and chose not to, and maybe others were never going to buy an iPad, but happily bought something less expensive.

Apple would be crazy to continue to ignore that market, for two reasons.  Firstly, because it clearly is a major market with huge potential for manufacturers.  The second point brings us to a new aspect of tablets and the overall computer and digital/cloud ‘eco-system’.

Tablets and Phones are Increasingly Razors

We have already seen how cell phones are treated like razors – you give them away to lock the owner into a particular brand of razor blades.  In the case of cell phones, it is of course being locked to a particular wireless service provider.

This is now extending to tablets too – and indeed, with tablets that have cell phone data connectivity, sometimes again with wireless service provider subsidies.

But the evolving really big ongoing revenue stream from tablets (and phones) is becoming more and more the provision and consumption of ‘digital content’.  Apps, games, music, and video in particular, cloud storage and other services to a lesser extent.  Whether it be via the umbrella Apple iTunes store, the Google Play Marketplace, or Amazon’s growing content services too, a person owning a tablet represents as an ongoing revenue stream to the company that provides its infrastructure.  Apple keeps 30% of every dollar you spend in its iTunes store, and over time, that becomes a major sum.

This is the second reason why Apple needs to respond to this huge new market for smaller tablet devices.  It is also the reason why first Amazon and now Google are selling their tablets with razor thin or even non-existent margins – they figure they’ll get their profit from ongoing sales to the device’s owner.

If a person has an Android phone, it clearly makes sense to also get an Android tablet, and – cautionary note for Apple – if a person with an iPhone buys a $200 Android tablet, when they decide to upgrade their phone, they’re going to be sensibly favoring an Android phone so as to make the user experience and content sharing homogenous across both their devices.

If Apple doesn’t have a $200 priced tablet, it stands to see its iPhone market erode as people who bought $200 Android tablets subsequently shift to Android phones, too.

In a Perfect World

In a perfect world, we see a person with possibly three different sized portable/mobile devices.

The first would be a phone, with the largest possible screen size possible for a phone that can still fit in a man’s dress shirt pocket.  This seems to be about 4.5″ – 5″.  The phone would have an about 300 pixel per inch density on its screen.

The second would be a tablet that can fit in a jacket/coat pocket, and weighing less than 1 lb.  Depending on how small the bezel around the screen can be made, this will probably allow for about an 8″ screen.  It should have about a 250 pixel per inch density on its screen – in other words, a bit larger than a Nexus 7 and with a slightly greater pixel density.

The third would be a tablet slightly larger than an iPad, and with a screen size almost the same as on a sheet of 8.5″ x 11″ paper – in other words, about a 13.5″ screen, and with a pixel density in the low 200s – perhaps 2350×1800.  It would probably weigh 2.5 lbs, maybe slightly more.

This third device would be both a pseudo/combo tablet and also a regular computer, and would be offered with a decent keyboard option, very similar to how Microsoft will be selling its smaller and generally inferior but very pricy Surface.

Our recommended ‘ideal’ phone is already available, the other two devices not yet so.  Until the time they are developed, your best strategy is to get the biggest phone screen you can, then decide if you’d prefer Apple’s slightly ‘too big’ iPad or Google’s slightly ‘too small’ Nexus 7 for an tablet, and until the third device starts to appear, combine the two with a regular laptop.

Note :  See our updated additional article about the best tablet screen size too.