Tablet sizes, meet UX

Now that there’s finally a useful selection of Android tablets out there (with decent 3.2 software and dual-cores), the market is feeling it’s first round of heat. Funny thing, no one seems able to decide what size to produce or market. Samsung has left it up to the users, and is about to offer 7″, 7.7″, 8″ & 10.1″ screens. And there’s a huge point to note: Apple’s 9.7″ isn’t widescreen, and it has as much surface-area than any other tablet offering. 10.1 sounds like more, but it’s negligibly bigger: .25″ square.

Experimental Question: So with all these screen sizes, I’m left to wonder, what’s the use-cases? When would a 7″ be more interesting or useful than the 9.7 or 10.1″?

Control: With a little quick-and-easy user-testing, I held my phone at a readable distance. Turns out to be around 15″-22″ from my eyes, depending on how engrossing the content, or in-motion I am.

Method: The 7 & 10″ tablet tests, I had to provide a stand-in, since I don’t own any tablets. I’ve made paper-cut outs of the screen sizes, and moved them at a distance to see when my phone distance would “eclipse” the paper screens.

Results: Turns out, a 4″ phone at 20″ is the same as a 7″ tablet at 34″. At the 15″ distance, the 7″ tablet is 25″ away, which is my arm at 90-degrees (forearm parallel to ground). This is a pretty good distance for holding a tablet, I would presume. It’s relatively comfortable, and the higher resolution of 1024x600px should still be legible (3-4mm/character is figured, and that’s about what a print-out bill I have laying around is. I might find it easier to read by a small margin, if only the font was larger, or the 7″ was a tad closer.

Now, the handy bit about the 10.1″ screen, it’s the same size as a standard paper sheet folded in half. With the 15″ viewable distance of the phone, the 10″ screen is a lengthy distance of 33.5″. While sitting, that’s about 10″ too far beyond my lap for this 6′ male.

Conclusion: What I’m saying is this: with the differing use-distances, the 7″ tablet affords no greater viewable area (proportionally) than the 4″ phone. But since both the 7″ and 10″ tablet would comfortably be in my lap (~24″ away from my eyes), the 10″ affords more viewable area.

Discussion: It’s “obvious” that there’s more space on the 10″ than the 7″. What this in-home UX study shows is the reason the 7″ would ever be popular in the first place: people either don’t have a smartphone, or they don’t want to hold it at the 15″ distance. In fact, my 13″ laptop on my desk is exactly 24″ away from my eyes, and my arms are at 90 degrees – just by habit. Laptops have seemingly prepared the subconscious for this distance.

One factor not mentioned is font-size & pixels/inch. My laptop ppi is around 116. the 10″ tablet would be around 149/150. The 7″ tablet is 170ppi, and my phone is a whopping 233ppi. Yet I feel the important part is the number of fixed-width characters & lines are readable on each screen. Even if the 7″ had the same resolution as the 10″, this only means images would be sharper, and font-sizes smaller.

Finally, with the 7″ screen-width traditionally set at 600px, this is still thinner than most iPaddy websites at 768px. Even WordPress’ back-end minimum width is 765px. It would seem the world of 7″ tablets is fated to be turned landscape, or to be an oversized mobile view. We’ll have to see how this tested prediction pans out, especially with Amazon’s new 7-incher arriving soon.

Post-Script: The 7″ isn’t pocketable, but it is purse-able. I’ve noticed many more women with 7″ e-readers on public transit than men with the spacious luxury of briefcases or manbags (both of which could support the 10″ screen). In public spaces, the 7″ feels more personal. A 13″ laptop screen is hardly able to be hidden in any respect, let alone from public view. A 10″ is halfway in between, approaching a share-ablility margin.

In other news, Apple screens are all odd-numbered: 1.5 nano, 3.5 iPhone, 9.7 iPad, 11″, 13″, 15″, 17″ Macbooks, 21″, 24″ iMacs.