I’ve noticed that finding the correct format for an e-book cover is not exactly easy. Even if you manage to find a guide on the publishing website you intend to use you soon find the documents are filled with jargon and useless information that serves only to confuse. So what I’ve done is break it down to the essential information. Please remember though that some of these formats are quite different from each other and I’d recommend you tweak your cover layout somewhat for each one. If I have missed any format out please let me know and I’ll add it. So in no particular order here is the only information you actually need:

Barnes and Noble (for Nook)

Aspect ratio:1.2

Image size: 600 pixels wide 730 pixels high.
DPI: 100
File size limit: 2 MB
Format: JPG (Maximum quality should not take the file size over the limit)

Kindle and Book Baby

Aspect ratio:1.6

Image size: 2820 x 4500 pixels (previously 1563 x 2500 pixels)
DPI: 72
File size limit: no limit specified
Format: JPG (Maximum quality should not take the file size over the limit)

Smash Words and Kobo

Aspect ratio:1.5

Image size: 1600 pixels wide x 2400 pixels high
DPI: 72
File size limit: 2MB
Format: JPG (Maximum quality should not take the file size over the limit)

LULU

Aspect ratio:1.3

Image size: 612 pixels wide x 792 pixels high
DPI: 72
File size limit: 2 million pixels
Format: JPG (Maximum quality should not take the file size over the limit)

Apple iBook

You need two covers for Apple.

1. Sales image:

Aspect ratio:1.6

Image size: 1563 pixels wide x 2500 pixels high.
DPI: 72
File size limit: none
Format: JPG (Maximum quality should not take the file size over the limit)

2. Internal cover (you can just reduce the sales image by 70% for this)

Aspect ratio:1.6

Image size: 1094 pixels wide x 1750 pixels high.
DPI: 72
File size limit: 2 million pixels
Format: JPG (Maximum quality should not take the file size over the limit)

If anybody finds anything to be incorrect please let me know in the comments. As far as I am aware these sizes are correct but it won’t hurt to double-check for yourself.

Of course, this may seem a bit daunting so it may be worth remembering that I only charge $15 per format to tweak your cover layout and provide a suitable file.