What is the best display aspect ratio for tablets?

One marked difference between current tablets is the aspect ratio of their displays. This blog post explores the pros and cons of the different aspect ratios, along with the question whether one of them is best overall.

The aspect ratios of current tablet displays

Device	Size	Normalized aspect ratio
Apple iPad mini	768px × 1024px	96 × 128
Apple iPad	1536px × 2048px	96 × 128
Google Nexus 7	800px × 1280px	87.636 × 140.217
Google Nexus 10	1600px × 2560px	87.636 × 140.217
Microsoft Surface	768px × 1366px	83.118 × 147.838
TV	3:4	96 × 128
DVD	9:16	83.138 × 147.802
Anamorphic (movie theaters)	1:2.39	71.704 × 171.372
Letter	8.5in × 11in	97.444 × 126.104
A4	210mm × 297mm	93.212 × 131.828

The last column shows the aspect ratio normalized to an area of 12288 (96 times 128). That is, all areas in that columns are the same, only the sides of the rectangles are different. The formula for the factor n with which the sides have to be multiplied is:

$$n=\sqrt{\frac{12288}{\mathit{width}·\mathit{height}}}$$

The rectangles look as follows.

Tablet display aspect ratios

Film aspect ratios

Paper aspect ratios

Is there a perfect aspect ratio?

Current tablets are optimized for different applications:

Watching movies on the iPad

• Among the tablets covered here, the iPad works best in portrait orientation. Its display has the “widest” aspect ratio of all tablets. That aspect ratio is the same as those of XGA displays and TVs. It is also close to Letter paper. Note that the Kindle Paperwhite that is clearly optimized for being used in portrait orientation, has the same display aspect ratio as the iPad (768 × 1024 pixels). Alas, the iPad works less well for movies where black bars mean that you lose quite a bit of display space.
• The Surface works best for watching movies. Its resolution (between 1365$\frac{1}{3}$ × 768 and 1366 × 768.375) is almost 16:9, the aspect ratio of DVDs and many notebook screens.
• The Nexus is situated between the extremes iPad and Surface. It is less elongated than 16:9.

Is there such a thing as a perfect display aspect ratio for tablets? No, because the closer you get to optimal for movies, the less suited you are for being used in portrait mode. There is, however, a good compromise: notice that A4 paper is between the iPad and the Nexus when it comes to elongation. It is used widely internationally and works well in portrait mode. A4 has the interesting property that the aspect ratio remains the same if you split it in half. This property is called the Lichtenberg ratio. While A4’s aspect ratio is not as good as the Nexus’ (let alone the Surface) for displaying movies, it is still better than the iPad’s.