Book Formatting Mistakes That Get Your KDP File Rejected (And How to Avoid Them)
The most common reasons a KDP file gets rejected in 2026 are: a wrong or mismatched trim size, margins and gutters that are too small for the page count, fonts that aren't embedded, images below 300 DPI, spine text on a book under 79 pages, bleed set up incorrectly, and stray elements in the PDF like crop marks, comments or placeholder text. Almost every rejection traces back to a spec mismatch between your file and KDP's requirements — not to your writing. The fix is to match KDP's Paperback Submission Guidelines exactly before uploading: set the document to your precise trim, embed all fonts, flatten transparency, keep every image at 300 DPI, and use scaled gutter margins. Below is each mistake, why it triggers a rejection, and how to avoid it — so your file passes the first time.
1. Wrong or mismatched trim size
If your document dimensions don't match the trim size you selected in KDP, the file is rejected or the preview shows content off the page. Worse, trim size can't be changed after publishing — pick wrong and you republish from scratch, losing reviews. Fix: set your document to the exact trim (e.g. 6″×9″) before you write a word of layout, and confirm it matches your KDP selection.
2. Margins and gutters too small
Text that runs too close to the edge or disappears into the spine is a top rejection cause. KDP requires an outside margin of at least 0.25″ (0.375″ with bleed) and a gutter (inside) margin that scales with page count:
| Page count | Minimum gutter |
|---|---|
| 24–150 | 0.375″ |
| 151–300 | 0.5″ |
| 301–500 | 0.625″ |
| 501–700 | 0.75″ |
| 701–828 | 0.875″ |
Fix: use the correct gutter for your length and add a little extra for readability — thicker books need more inside margin so text doesn't vanish into the binding.
3. Fonts not embedded
If your fonts aren't embedded in the PDF, KDP can't reproduce them and substitutes or rejects the file, wrecking your layout. Fix: embed all fonts on export (in most tools this is a checkbox), or export to PDF/X, which embeds by default.
4. Images below 300 DPI
KDP requires all images — cover and interior — to be at least 300 DPI. Low-resolution images (especially screenshots or web images) look blurry in print and trigger quality warnings. Fix: use 300-DPI source images sized at their final print dimensions; don't upscale small images.
5. Spine text on a book under 79 pages
KDP only prints spine text on books with more than 79 pages — thinner spines can't hold legible type. Adding spine text to a shorter book gets the cover rejected. Fix: if your book is under 79 pages, leave the spine blank, or add genuine content/front-and-back matter to cross the threshold.
6. Bleed set up incorrectly
If images are meant to run to the page edge but the bleed is wrong, you get white slivers or trimmed content. Fix: for full bleed, extend images 0.125″ past the trim on top, bottom and outer edges, and size the PDF 0.25″ taller and 0.125″ wider than the trim. If you have no edge-to-edge images, use no bleed.
7. Stray elements left in the PDF
KDP rejects files containing crop marks, trim marks, bookmarks, comments, annotations, invisible objects, placeholder text or leftover metadata. Fix: export a clean, single-page PDF (not spreads), flatten layers and transparency, and remove all markup before uploading.
Cover-specific rejections (separate from the interior)
Your cover is reviewed separately from your interior, and it has its own failure modes that catch authors off guard:
- Wrong spine width: spine width depends on exact page count and paper type (white 0.002252″/page, cream 0.0025″/page). Guess it and your text and art drift onto the wrong panel. Always use KDP's cover template generator for your final page count.
- Text too close to the spine or trim: keep important text at least 0.125″ from all edges and 0.0625″ clear of the spine folds, or it risks being cut or wrapped.
- Cover doesn't match interior page count: if you revise your interior and the page count changes, the spine width changes too — you must regenerate the cover.
- Low-resolution cover: the whole wrap must be 300 DPI; a cover that looks fine on screen can fail at print resolution.
- Missing bleed on the cover: covers always need full bleed; art must extend past the trim on all outer edges.
Because the spine width is tied to page count, the cover is the single most common thing authors have to redo after a late interior edit. Finalize your interior first, then build the cover to its final page count.
Your pre-upload checklist
Run through this before every KDP submission to clear the review on the first try:
- Document set to the exact trim size you selected in KDP.
- Gutter margin correct for your page count (0.375–0.875″).
- All fonts embedded; transparency and layers flattened.
- Every image ≥ 300 DPI, interior and cover.
- Single-page PDF, no spreads, no crop marks, comments or bookmarks.
- Spine text only if 79+ pages; cover spine width matches final page count.
- Bleed set correctly (or none if no edge-to-edge art).
- Previewed every page in KDP's online previewer.
The fastest way to guarantee a first-time pass
You can avoid every rejection above by checking each spec by hand — or by having files prepared correctly from the start. DIY works if you're careful and patient; the risk is the re-upload cycle, where each fix means re-exporting and waiting for another review.