The email lands and rarely explains itself. "Your file does not meet our printing requirements," followed by a list of links to KDP's help pages without specifying which line, which margin, which measurement caused the rejection. The temptation is to make a small change and resubmit; the better move is to work out which of the standard reasons it actually was. Most rejections fall into one of seven categories.
The list below is ordered roughly by how often each cause appears in indie author forums and KDP community threads. The fix sits at the end of each section. Reupload only after you've identified the cause — a fresh upload of the same file is the same rejection.
1. The spine is the wrong width
By far the most common reason a cover is returned. The cover was sized when the interior was a draft, the interior then gained or lost pages before final export, and the cover was uploaded against the new page count. The spine no longer matches the book.
KDP catches this because it compares the cover's spine area against the spine width it calculates from the uploaded interior PDF's page count and paper type. If the two disagree by more than a hair, the cover is rejected.
Fix: Wait until the interior is final. Note the exact page count from the exported PDF. Recompute the spine: page count × 0.002252 in (black and white on white paper), 0.0025 in (black and white on cream), or 0.002347 in (premium colour on white). Resize the cover. See the cover-size walkthrough for the full formula.
2. Bleed is missing or applied twice
A cover is required to bleed by 0.125 in (3.175 mm) on every outer edge. KDP rejects cover files that stop at the trim line, because the trimming blade always overshoots a fraction; without bleed, the print arrives with thin white edges where the ink should run to the cut.
The opposite mistake also rejects: bleed counted twice, producing a cover 0.25 in too large on each axis. This usually happens when a cover-design tool exports with bleed already added, and the author adds their own bleed on top.
Fix: Check whether your cover-design tool exports with bleed included. Then size the file so the total dimensions are exactly (2 × trim_width) + spine_width + 0.25 in wide and trim_height + 0.25 in tall. Not more. Not less.
3. The file is not a flattened PDF
KDP requires the cover as a flattened PDF. Layered files, files with active OpenType features, files with editable text and unflattened transparencies frequently fail. A cover exported from a design tool without an explicit "flatten" step often carries hidden layers that confuse the print preflight.
Fix: Export the cover as a PDF/X-1a:2001 file if your tool offers it; otherwise as a standard PDF with all transparencies flattened and all fonts embedded or outlined. JPEG, PNG and TIFF are not accepted for the final cover upload, even though they may have been the working format during design.
4. Image resolution is below 300 DPI
KDP requires all printed images to be at least 300 dots per inch at their final printed size. A cover image that looked sharp on screen because it was resampled to fit the canvas often resolves to 150 DPI or less when measured against its actual printed dimensions.
The most common cause is dragging a 1,200 × 1,800 px image into a 6 × 9 in canvas. On screen it looks fine. At print resolution it is 200 DPI, which prints visibly soft and is rejected.
Fix: For a 6 × 9 in cover with 0.125 in bleed all round, the source artwork should be at least 6.25 × 9.25 in at 300 DPI — that is, 1,875 × 2,775 pixels minimum. Larger is fine; smaller is the rejection.
5. Text or detail lands inside the barcode area
KDP places the ISBN barcode in a rectangle 2 in wide by 1.2 in tall, positioned 0.25 in inside the trim from the bottom and outer edges of the back cover. If your cover artwork has copy, illustration, an author photograph or a fine detail in that area, KDP overlays the barcode on top of it.
This isn't always a rejection — sometimes the cover prints with the barcode obscuring part of your design. But when the safe zone is occupied by something legally or commercially important — a back-cover blurb, a quotation, a publisher logo — the cover is frequently held for review and either rejected or printed with a damaged composition.
Fix: Treat the bottom-right 2 × 1.2 in of the back cover (with a 0.25 in offset from the edges) as off-limits for anything that matters. Many indie covers reserve the area as a plain panel — a darker rectangle, a band of colour, or simply background. The barcode then sits cleanly on top without visual conflict.
6. Cover trim does not match interior trim
The interior PDF says 5.5 × 8.5 in. The cover PDF says 6 × 9 in. KDP rejects the pair because they cannot be bound into the same book. This sometimes happens when a cover is reused from a previous title at a different trim, or when a designer is briefed against the wrong dimensions.
Fix: Confirm both files declare the same trim before uploading. The interior PDF's page size should match the front-cover area of the cover PDF exactly, with the cover wider by spine_width + 0.25 in and taller by 0.25 in. If they disagree, one of the two was made wrong.
7. Spine text on a book that is too thin
KDP does not allow spine text on books under 79 pages. The spine is too thin to print legible type, and a smudged or misregistered spine title looks worse than no title at all. If a cover for a 60-page book includes spine text, the cover is rejected.
Fix: Either pad the book to 79 pages or more — front matter, back matter, blank pages — or remove the spine text entirely. A spineless cover for a thin book is acceptable, and reads as a deliberate choice rather than an oversight.
The discipline behind a clean upload
The arithmetic for any cover is simple. The discipline is in finishing the interior first, computing once against the final page count, and exporting one flat PDF with bleed, the correct trim and a clear barcode zone. Most rejections trace back to skipping one of those steps under time pressure.
A small checklist that prevents the majority of returned files:
- Interior PDF exported and page count recorded
- Spine recomputed against final page count and paper type
- Cover dimensions verified:
(2 × trim_width) + spine_width + 0.25 inbytrim_height + 0.25 in - Bleed present once, not zero, not twice
- Cover trim equals interior trim, to the decimal
- All images at least 300 DPI at printed size
- Barcode safe zone left clear
- Exported as flattened PDF with fonts embedded or outlined
- Spine text removed if page count is below 79
Where Folio Format fits
Folio Format runs cover and interior checks before any export leaves the studio. The spine width recomputes as the page count changes. The barcode safe zone is overlaid in the cover canvas. The trim is read from a single source and used by both sides of the export. When something is off, the studio explains which line of the cover formula has gone wrong, not just that the file failed.
Last checked 22 May 2026. Always confirm current Amazon KDP and IngramSpark specifications before uploading final files. Folio Format is designed to help users export KDP-ready files and catch common publishing issues before upload; it makes no claim about platform acceptance.