How do I calculate the full wrap size for a KDP paperback cover?

The full wrap width is 0.125 inch bleed, plus the back cover trim width, plus the spine, plus the front cover trim width, plus 0.125 inch bleed. The wrap height is your trim height plus 0.25 inch (0.125 inch bleed on the top and bottom). The spine width is your page count times 0.002252 inch for white paper or times 0.0025 inch for cream paper. Build the file at that full wrap size at 300 DPI, not at your trim size.

Why does KDP keep rejecting my cover file?

The most common causes are: the file was built at trim size instead of the full wrap, the wrap size does not match the page count so the spine is wrong, text or the barcode sits inside the 0.25 inch trim safety zone, images are below 300 DPI, or spine text was added to a book under about 79 pages. Rebuild on the KDP cover template for your exact page count and trim, keep text roughly a quarter inch inside the trim edges, and upload a flattened PDF.

Does KDP accept RGB covers?

Yes, KDP accepts RGB and converts it to CMYK for printing, so an RGB cover is not itself a rejection. The catch is that the conversion can shift your colors, especially bright blues, greens, and rich blacks. If exact color matters, supply CMYK values you have already reviewed. This is different from IngramSpark, which requires CMYK and will reject RGB.

Does KDP hardcover use the same cover math as paperback?

No. KDP hardcover is a case laminate cover with wrap and hinge allowances that make it larger than the trim, and its spine width table differs from the paperback formula. It also differs from IngramSpark hardcover math. Always download the KDP cover template for the specific hardcover trim and page count rather than reusing paperback numbers.

Author Guides · Covers · KDP

KDP rejected your cover? Every error, decoded

By Tracy Atkins, founder of BookDesigner.ai and BookDesignTemplates.com · 15+ years of print files, 70,000+ authors · Updated June 27, 2026

The short answer: almost every KDP cover rejection comes down to one thing, your file was not built at the correct full wrap size for its exact page count. A print cover is one flat sheet that covers the back, the spine, and the front all at once, plus bleed. If you built it at trim size, or the spine is wrong because the page count changed, KDP stops it. The math and every common error are below.

The rejection message, decoded

KDP's cover errors are terse. You will usually see something like this in the print previewer or an email:

Errors found: Your cover dimensions do not match the requirements for this book. Expected full-bleed size for your page count and trim. Please review and re-upload. · Content beyond the trim edge / inside the margin was detected.

KDP computes an exact expected cover size from three facts: your trim size, your page count, and your paper type (white or cream). Its preflight measures your PDF. If the numbers disagree, the file is rejected. Nothing about your artwork is being judged here; this is a measurement problem, and it is fixable in an afternoon.

The KDP paperback cover math

A paperback cover is a single wrap. Here is exactly how KDP calculates the size it expects.

Full wrap width

Add these five pieces, left to right:

0.125" bleed (left edge)
back cover trim width
spine width
front cover trim width
0.125" bleed (right edge)

So for a 6×9 book: 0.125 + 6 + spine + 6 + 0.125. The two trim widths are your front and back, and they are identical.

Full wrap height

Height is simpler: trim height + 0.25", which is 0.125" of bleed on the top and 0.125" on the bottom. A 6×9 wrap is 9.25" tall.

Spine width

White paper: page count × 0.002252"
Cream paper: page count × 0.0025"

A 300-page white-paper book has a spine of 300 × 0.002252 = about 0.676". Change the page count and the spine changes, which is why a cover that fit last week gets rejected after you edited the interior. If you want the full breakdown across every paper stock and both printers, see our book spine width guide.

The safe zones that get covers rejected

Even a correctly sized wrap fails if content sits where it should not:

Keep all text roughly 0.25" inside the trim edges. Trimming has tolerance, and anything closer risks being cut off, which the previewer flags.
Give the spine about 0.0625" (1/16") of side clearance. Spine text that runs to the fold edges will look crooked because the fold itself has tolerance. Center the title in the spine and leave breathing room on both sides.
Spine text needs a spine wide enough to hold it. As a rule of thumb, you need roughly 79+ pages before there is enough spine to safely print text on it. Thinner books should leave the spine blank.

The barcode: let KDP place it, or clear the space

If you do not supply your own barcode, KDP prints one automatically in the lower-right area of the back cover. Leave that region clear of important art and text, or the auto-placed barcode will sit on top of your design. If you do supply a barcode, put it in that same zone on a clean, light background.

File format that passes

KDP prefers a PDF, flattened, with fonts embedded, built at the full wrap size at 300 DPI. A few file-level notes that catch people:

RGB is accepted at KDP. KDP converts it to CMYK for print. That conversion can shift colors, especially bright blues and greens and rich blacks, so review the printed proof or supply reviewed CMYK values if exact color matters. (This is the opposite of IngramSpark, which requires CMYK and rejects RGB. See our IngramSpark cover rejection guide.)
Flatten transparency and layers. Live layers and effects can render unpredictably in print.
Embed every font. Missing fonts substitute silently and change your typography.

Every common KDP cover rejection, in one table

What happened	The fix
Wrong wrap size for the page count	Recompute the spine from the current page count and rebuild the full wrap; download a fresh KDP template
Cover built at trim size, not full wrap	Rebuild as one sheet: back + spine + front + 0.125" bleed all around
Text inside the 0.25" trim zone	Pull all text and logos at least a quarter inch in from every trim edge
Spine text on a thin book	Remove spine text under about 79 pages; keep 1/16" clearance otherwise
Low-resolution images	Replace with 300 DPI art measured at final print size
Barcode area covered	Clear the lower-right of the back cover for the auto-placed barcode
Colors shifted after upload	Expected: KDP converts RGB to CMYK; review a proof or supply reviewed CMYK
Reused paperback math on a hardcover	Hardcover case laminate uses different wrap and spine math; download the hardcover template

Hardcover is a different animal

KDP hardcover is a case laminate cover, not a paperback wrap. It has wrap-around and hinge allowances that make the cover larger than the trim, and its spine width comes from a different table than the paperback formula above. It is also not the same as IngramSpark's hardcover math. Never reuse paperback numbers on a case laminate; download the KDP cover template for the specific hardcover trim and page count, and read the spine straight off it. Our spine width guide walks through why the hardcover numbers diverge.

Or skip the geometry homework entirely.

BookDesignerAI builds complete cover file sets, KDP, IngramSpark, and Lulu, each to that printer's own template math, alongside a press-ready interior. Interior is $99.99, a cover is $99.99, and the Full Package is $249.99. Cantos, our book-design AI, handles the wrap, spine, bleed, and barcode; you approve the design. See your own book first: upload your manuscript and get a free 30-page professionally typeset preview at bookdesigner.ai/preview. No credit card, and nothing is ever trained on your work.

Get the Free Preview

Sources: Amazon KDP paperback and hardcover cover guidelines and print specifications; spine multipliers per KDP's published paper calipers, reviewed June 2026. Related: Book spine width: the real formulas · IngramSpark cover rejections, decoded · Your book is stuck in review · All author guides