Book Cover Design Aspect Ratio 8:5 or 1.6

When you’re uploading your cover on Amazon.kdp, you’ll notice they require that your cover’s ratio be 1.6.: 

"Dimensions

Requirements for the size of your cover art must have an ideal height/width ratio of at least 8:5 (1.6), meaning:

• A minimum of 625 pixels on the shortest side and 1000 pixels on the longest side 
• For best quality, your image should be 2500 pixels on the longest side 

Important: We cannot accept any images larger than 10,000 pixels on the longest side." 

Put more succinctly, it means that the height of the image is 1.6 times the width. For example, if the width is 1500 then the height must be 2400. (1500 x 1.6 = 2400.) The obvious reason for this requirement is that most computer screens, tablets, and smart phones have an aspect ratio of 16:10 A.K.A 8:5, which means that these screens have a width 1.6 times their height. Interestingly, the 2014 Kindle Fire Tablet screen size was 1280 x 800 (1.6), and the xtra large Kindle Fire was 2560 x 600 (1,6), but the 2015 large size was 1024 x 600 (1.7).

The way the guideline is worded, there doesn't seem to be much leeway, but I like to think that 1.6 is only a recommendation. A quick search on the web will show that 1.5 is preferred by many graphic artists and cover designers, myself included. Why? As much as I like the golden ratio (1.618), for a book cover I find it too narrow. Many Tradeback books are 1.5. 

The popular 6 x 9 size is 1.5.  

5 ½ x 8.25 is 1.5. 

On the other hand, Mass Market books, the ones you find in grocery stores, are 4.25 x 7, which comes to a ratio of 1.64. 

It’s really a matter of taste.

One important thing to consider: if your covers are all 1.5 or 1.6, regardless of their size, you won’t have a problem making them uniform when you re-size them. For instance, when you're uploading them onto your website, or when Amazon automatically re-sizes them on your author central page, if they're all the same ratio, they'll line up like tin soldiers. Notice that my covers on this blog's sidebar all appear uniform, despite the fact they're different sizes. 

Here's a side by side comparison. 1.6, 1.5, and 1.4 (1.37 to be exact). It's just my personal preference, but I like 1.5 best.

Remember the ratio!