I’ve seen a lot of posts just lately asking about what size artwork should be for Book covers. Here is a complete list of all book sizes
For the most part they are talking about artwork for Amazon/and kindle so I’m going to address that.
Paperback Books
The size of a paperback book is known as “Octavo” which is 6 inches (152mm) wide by 9 inches (228.5mm) tall. The ratio is 1.5
The size requested by Amazon for Kindle is slightly different. They simply give a ratio of 1.6 which comes out at 5.623 inches (142.8mm) wide x 9 inches (228.5mm) high.
Final artwork for print needs 300 dpi at actual size. This is industry standard, so that means that for an Octavo paper back cover your final artwork should be 6 x 9 inches at 300 dpi or 1800 pixels x 2700 pixels.
If we apply the same thinking to Amazon the final artwork would be 5.623 x 9 inches at 300 dpi or 1687 pixels x 2700 pixels. However Amazon specify a limit on the maximum pixel height of 2500 pixels. This means your final art will be 5.623 x 9 inches at 277.77 dpi or 1562 pixels x 2500 pixels.
Now the important part:
I recomend you always work to cater for the “Octavo” (6 x 9) format which will allow a little room at either side to crop for Amazon’s 1.6 format.
If you are digitally painting or photo compositing you should always work at least half up. That is 6 x 9 at 450 dpi or 2700 pixels wide x 4050 high.
This allows for a reduction to 67% which will hide any minor blemishes in your compositing or art. Obviously for Amazon the reduction is slightly more: 61.73% to be precise.
Remember its always possible to reduce an image but enlarging one past 120% will give unacceptable quality and pixilation will be seen on the print.
Free Photoshop Template
Anyway this all seems extremely complex but don’t worry I made a free Photoshop template for you. Its set up as 6 x 9 at 450dpi at actual size with an Amazon Kindle template overlaid. It also features a Golden ratio template and a rule of thirds template to help with composition.
Right click and save here to download it
Let me know if you need anything else like this and I’ll see what I can do.
keithdraws 
Your site has a wealth of information for which I am grateful. Thank you so much for your explanation of the 1:6 aspect ratio and template. I’ve been a print designer for a very long time and never had to use it. I realize now after all this time that algebra WOULD be useful afterall.
Hello Keith, Thank you for your article on book cover sizes. My question is a bit different. If I am doing traditional original artwork for an A4 sized coloring book, what should be the dimensions of my original artwork? My interior pages I am doing on A4 and scanning at 600 dpi. For the cover I am thinking of doing a double page spread so that I have artwork on the spine. I appreciate your feedback.
Hi Jim, That really does depends on what printer you are going to use, so it is best to talk to them. Sorry, I can’t be of more help.
Hi Keith, No problem. I appreciate your response. I think I figured it out with more research.