KDP Cover Requirements: Dimensions, Spine and DPI Explained

A KDP print cover is not a picture of the front of a book. It is one flat, unfolded file — back cover on the left, spine in the middle, front cover on the right — that will be wrapped around a physical book, trimmed, folded and glued. Get its width wrong by a few millimetres and the spine text drifts onto the front, the barcode collides with your blurb, or KDP simply rejects the file. The design can be beautiful and still fail. The dimensions have to come first.

This guide explains how the total size is calculated, why paper choice changes the spine, when spine text is allowed, and the mistakes behind most rejections — paperback in detail, hardcover briefly, and the separate ebook cover at the end.

How the full-wrap size is worked out

KDP gives the formula directly in its paperback cover guidance. You do not guess the canvas size; you build it from five pieces, left to right:

• Cover width = bleed + back cover width + spine width + front cover width + bleed
• Cover height = bleed + trim height + bleed
• Bleed is 0.125 in (3.2 mm) on the top, bottom and outside edges — every print cover has bleed
• Back and front cover widths are each your trim width; there is no bleed between the panels and the spine

Worked example: a 6 x 9 in paperback, 250 pages on white paper. Spine = 250 x 0.002252 in = 0.563 in. Full width = 0.125 + 6 + 0.563 + 6 + 0.125 = 12.813 in. Height = 0.125 + 9 + 0.125 = 9.25 in — at 300 DPI, 3,844 x 2,775 pixels. Change page count, trim or paper and the numbers change, which is why a cover made before the interior is final will probably be made twice.

The spine: page count times paper thickness

Spine width is not a design choice. KDP calculates it from your final page count multiplied by a per-page thickness for your paper and ink type. For black-and-white books, white paper uses 0.002252 in per page and cream paper uses 0.0025 in per page. Cream is thicker, so the same manuscript produces a wider spine — on 250 pages, 0.625 in on cream against 0.563 in on white. For colour books, KDP lists premium colour paper at 0.002347 in per page and standard colour paper at 0.002252 in per page. Whichever combination you use, lock three things before anyone designs the spine: final page count, trim size, and paper type.

Add a chapter, change your margins, or switch from white to cream, and the spine moves. A designer working from an early draft will centre spine text perfectly — on a spine your finished book does not have. Finish the interior, note the page count KDP shows for the uploaded file, and only then brief the cover.

When can you put text on the spine at all?

Only on a thick enough book. KDP says a book must have at least 79 pages to include spine text, and that it only prints spine text on books with more than 79 pages — in practice, plan on 80 pages or more, which is also the minimum KDP's Cover Creator uses for spine text. Below that, leave the spine blank or use colour and artwork with no lettering. Even when text is allowed, it needs at least 0.0625 in (1.6 mm) of clear space on either side, so it does not wrap onto the front or back when the book is bound. On a just-eligible book that leaves very little room: a short title in a clear, bold face is all that will fit honestly. Binding also varies slightly from copy to copy, so never set spine text edge to edge.

Resolution, file format and flattening

KDP requires cover images placed at 100% size at a minimum of 300 DPI, flattened to one layer. A screen-resolution image will look soft in print, and no export setting can invent detail that was never in the source. If an image is not sharp at printed size, replace it rather than enlarging it.

The finished print cover must be a single PDF containing back, spine and front as one image. Before export, flatten all transparencies — unflattened transparency can print with missing or distorted content — embed your fonts, and remove crop marks, colour bars, template text and any guides. Do not lock or password-protect the file, and do not include spot colours; KDP recommends converting them to CMYK and notes that colour profiles are removed before printing. KDP also advises keeping cover files to 40 MB or less where possible, even though the hard conversion limit is much higher, because very large files slow printing.

For colour, KDP's guidance asks for images in CMYK for print. Working in CMYK from the start avoids the dull surprise of converting a vivid RGB design at the last step, though print-on-demand colour always has an accepted tolerance.

Safe zones and the barcode area on the back

Trimming and folding have a small, normal variance, so important content needs a buffer. KDP asks that front and back text be at least 0.125 in (3.2 mm) inside the trim lines, with no text extending into the spine area. Treat that as a minimum — keep titles and key artwork comfortably inside, away from edges and folds. Borders are risky for the same reason, and KDP does not recommend them. Text should be at least 7-point and contrast clearly with its background.

Look at the lower right corner of your back cover — part of it is not yours. Without a barcode, KDP places one there automatically, in a white box 2 in (50.8 mm) by 1.2 in (30.5 mm). Keep it free of text and important images; anything there will be covered and can cause rejection. If you supply your own, it needs the specified size, at least 0.25 in from the edges, 100% black on white, right way up, matching your ISBN. For most authors, leaving the area clear for KDP is simpler and safer.

Design the back cover backwards: reserve the barcode corner first, place the blurb and author bio around it, and only then add decoration.

Hardcover: same idea, different construction

A hardcover cover follows the same logic — back, spine, front in one PDF — but it is not a paperback file relabelled. It wraps around rigid boards and folds over their edges, with hinge areas near the spine. That makes the file larger than the paperback equivalent and outside the simple bleed formula. Generate the hardcover template for your exact trim, page count and paper in KDP's calculator and build on that.

The ebook cover is a different file entirely

Your Kindle cover is front only: no spine, back, barcode or bleed. It is a single JPEG or TIFF image, in RGB, under 50 MB. KDP's ideal dimensions are 2,560 pixels high by 1,600 wide — a ratio of at least 1.6:1 — with minimums of 1,000 high by 625 wide and a maximum of 10,000 pixels on either side. It works mainly as a thumbnail, so legibility at tiny size matters more than fine detail. For a white or very light cover, KDP suggests a narrow 3 to 4 pixel medium-grey border so it does not disappear against Amazon's white pages. Build it from your original design files, not by cropping the print PDF.

Use KDP's own tools before you improvise

KDP's Print Cover Calculator and Templates tool takes your binding, interior and paper type, trim size and page count, calculates exact dimensions, and provides a downloadable template to use as a guide layer. KDP also offers Cover Creator, its built-in tool, which builds a cover to specification from layouts and images — reasonable for a simple cover, with less control than professional design tools. Either way, hide or delete the template layer before export: anything left visible will print.

Why covers actually get rejected

Most rejections are not about taste. They are about geometry and file preparation, and they repeat across thousands of first books. Work through this list against your final file, not your working draft:

• Wrong total dimensions — usually a cover built before the final page count, or for a different paper type, so the spine is the wrong width
• Missing or incorrect bleed — background or images stop at the trim line instead of extending 0.125 in beyond it, leaving a white edge risk
• Low resolution — images below 300 DPI at printed size, or screen-resolution images enlarged to fill the cover
• Text outside the safe area — titles or names too close to the trim, or front and back text drifting into the spine
• Spine text on a thin book — lettering added below the 79-page threshold, or spine text without 0.0625 in clearance on each side
• Barcode problems — text or artwork left in the 2 x 1.2 in barcode area, or a supplied barcode that is the wrong size, not 100% black, or mismatched to the ISBN
• Unflattened or unfinished file — transparencies and layers left live, fonts not embedded, crop marks, template text or guides still visible, or a locked file
• Details that do not match — title, author name or edition on the cover differs from the details entered during title setup

Every item is checkable with the template overlaid and the PDF open at full size. Check before upload, use KDP's previewer after, and order a proof copy — the only place spine alignment, colour and trim can be judged as a reader will see them.

A cover must sell the book at thumbnail size and survive a press at full size. Meeting KDP's specifications lets the second happen without ruining the first. If you would like your cover built to template alongside your manuscript, Authorly works with founders and professionals in India to prepare books for Amazon KDP — begin at https://book.authorly.shop/start, at whatever stage your book is now.