KDP’s infamous rejection emails are notoriously unhelpful. A generic message like “your cover does not meet our specifications” could mean any one of a dozen things. The reasons are few, and they come in a fairly fixed order of likelihood.
1. Your PDF is the wrong size (literally)
This is the top culprit. KDP doesn’t want a file that’s roughly the right size; it needs one that’s exactly the right size, calculated to three decimal places. The required dimensions are a precise formula based on your trim size, your final page count, and your paper choice. Most authors trip up here in one of two ways:
- You forgot the bleed. Your file is sized to the trim dimensions (for example, 12.75″ wide) instead of including the extra 0.125″ bleed margin on each side (making it 13.0″ wide).
- Your spine math is off. You calculated the spine width using an outdated page count or the wrong paper caliper. White paper is 0.002252″ per page, while cream is 0.0025″. That tiny difference adds up — a 300-page book will have a spine 0.074″ wider on cream paper.
The fix: Recalculate everything from scratch using your final, confirmed page count and paper selection in the cover size calculator. Then, rebuild your entire design canvas to those exact dimensions. Be aware that a slightly-off file might sometimes sneak through upload, only to be cropped weirdly when printed. That specific headache has its own guide.
2. The resolution is too low for print
Your cover must deliver a crisp 300 dots per inch (DPI) at its full printed size. It’s a simple pixel math problem. If you stretch a 2000-pixel-wide image across a 13″ cover wrap, you end up with only about 154 DPI. That’s a guaranteed rejection, or worse, an acceptance that prints blurry. What counts is the raw pixel count, not the DPI tag. The formula is straightforward: required pixels = inches × 300. For a deeper dive into why the DPI number is often misleading, see this explanation.
3. Text or important graphics are in the danger zone
Anything you don’t want accidentally trimmed off needs a safe buffer. Keep all critical text and logos at least 0.25″ inside from the outer edge of the cover. Furthermore, any background color or image must extend all the way through the 0.125″ bleed area. If the checker sees a white sliver at the very edge of your file, it reads that as content placed in the trim zone and rejects it.
4. Spine-specific violations
The spine is a common failure point with two strict rules: - Placing any text on the spine of a book with fewer than 79 pages triggers an automatic rejection. The rules are clear and explained here. - Spine text must be kept at least 0.0625″ away from the fold on either side.
5. Invading the barcode’s territory
KDP automatically places a barcode in the lower-right corner of your back cover, in a zone roughly 2″ wide by 1.2″ tall. If you put any important text or a key logo inside that reserved area, your cover will be rejected. The detailed specifications for this space are here.
6. The cover doesn’t match the book’s metadata
This is a clerical error that causes human review flags. The title and author name on your physical cover must match exactly what you typed into KDP’s metadata fields. If you have a subtitle on the cover but not in the metadata (or vice versa), it gets flagged.
When none of the above applies
Sometimes, a cover is technically perfect but fails on content grounds. This includes using review-quote text that implies fake celebrity endorsements, or accidentally leaving a second barcode in your design. KDP’s rejection email usually carries one key word, “cover dimensions,” “resolution,” or “content,” and that word points to the category.
Sources
- KDP: Paperback Submission Guidelines — dimensions, DPI, spine, margins
- BookCoversLab: cover rejection checklist — pre-upload checks
