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From Page Count to Print-Ready Cover: One Book's Dimensions, Step by Step

One 6" x 9" novel on cream paper, taken from its final page count to a print-ready wrap canvas and a matching Kindle cover. Every measurement below is calculated, so you can follow along with your own numbers.

Published October 17, 2026. Figures are calculated from KDP's published rates when the page is built.

Three facts from the interior fix every measurement on a paperback cover: trim size, page count and paper. Here they are 6" x 9", 320 pages and cream, for a black-ink novel. Get one of them wrong and the spine comes out the wrong width, and every panel to the right of it moves.

So finish the interior first, export the PDF, and take the page count from that file rather than from a word-count estimate.

Step 1: the spine

KDP's paperback cover help page gives a thickness per page for each paper. Cream is 0.0025" a page, a little thicker than white. For our book:

Notice that trim size plays no part. A 320-page book has the same spine at 5" x 8" as at 6" x 9"; only the paper and the page count change it. The spine width calculator does this one sum for any paper type.

Can the spine carry text?

Yes. KDP prints spine text only on books with more than 79 pages, so 80 pages is the first even count that qualifies, and 320 is well past it. The same help page asks for at least 0.0625" (1.6 mm) between spine text and each edge of the spine, because every bound copy can shift slightly at the folds. Take that off both sides and the band you can set type in is:

Title and author name both have to fit across that width. It sounds generous until you try to fit a long title in a serif face; set the spine type first, then decide whether the title needs to be shortened there.

Step 2: the full wrap in inches and millimetres

The wrap is one image: back cover, spine and front cover side by side, with 0.125" of bleed on the outside edges, top and bottom. Here is KDP's formula, the one the cover size calculator runs, filled in for this book.

In millimetres that is 331.47 mm × 234.95 mm. One detail if you work in metric: KDP writes the bleed as "0.125" (3.2 mm)", but 0.125" is exactly 3.175 mm. Build the canvas from the inch figures and convert once at the end, instead of adding rounded millimetre values, and your file will match the size KDP expects.

Step 3: the pixel canvas at 300 DPI

KDP asks for cover images placed at a minimum of 300 DPI. Multiply each side by 300 and round up to a whole pixel, which is what the print DPI calculator does:

Set up a 3,915 × 2,775 pixel document with its resolution set to 300. Any photo or illustration you place on it needs at least as many pixels as the area it covers: a background image that runs across the whole wrap needs the full canvas size, while the front artwork alone needs 1,800 × 2,700 plus whatever bleed it touches.

Step 4: where each panel starts

Put guides on the canvas before you place anything. Measured from the left edge:

Several of those positions land on half a pixel, because a 0.125" bleed is 37.5 pixels at 300 DPI. Don't round the guides to whole pixels in your head. Most design apps accept a guide position typed in inches, so enter the inch value and let the app place it. Keep front and back cover text at least 0.125" inside the trim guides, as KDP's cover page asks.

The barcode area

KDP's cover help page says you can upload with or without your own barcode, and if you don't supply one, KDP places one on the back cover. The page text doesn't give a size for it. What it does say is that the template from KDP's cover calculator marks a "barcode margin", so download that template for your exact book and keep the marked area free of text and key artwork. For right-to-left books the page notes the barcode goes at the lower left of the back cover instead.

Step 5: the matching Kindle cover

The Kindle edition uses only the front panel, never the wrap. At 300 DPI the front panel (trim only, no bleed) is 1,800 × 2,700 pixels. KDP's eBook cover image page asks for a height-to-width ratio of at least 1.6:1; our panel is 1.50:1, a little too wide.

Keeping the full height, the Kindle cover is 2,700 ÷ 1.6 = 1,687 pixels wide, so 113 pixels come off the width. In print terms that is 0.19" from each side of the front cover. Two practical consequences:

• Design the paperback front with the title and author name at least that far inside the side trims, and one piece of artwork serves both editions.
• Export the Kindle file from the front panel area of the wrap: from 6.925" to 12.925" across and 0.125" to 9.125" down, then crop the width. The result, 1,687 × 2,700, is taller than the 2,500 pixels KDP's page recommends for the best quality on high-definition devices.

For other trims, the Kindle cover size calculator works out the same crop.

When the page count changes after proofing

Suppose the proof arrives and you decide to add an afterword, a reading-group section or a sample chapter of the next book. Say the interior grows by 20 pages to 340. Recompute everything that depends on the spine:

The height doesn't move, and neither does the Kindle cover, since the front panel is still 6" x 9". What moves is the spine and everything to the right of it. 15 pixels sounds small, but it is 0.025" on each side of the spine's centre line, and KDP allows only 0.0625" of variance at each fold. Spine text that was centred on the old file now sits off-centre, and a colour block that ended at the old fold now spills onto the front. The extra pages also add $0.24 to the Amazon.com printing cost of every copy, straight out of the royalty; the printing cost guide shows how that scales.

The fix is mechanical if the file was built well: widen the canvas by 15 pixels, add the space at the spine (not at an outer edge), move the front cover artwork right by 0.050", and re-centre the spine text. If your designer worked from a fixed template, send them the new page count rather than editing the file yourself. Then upload the new interior and the new cover together, never one without the other, and check both in the previewer before you approve.

More guides

• KDP Groundwood Paper: Cost, Eligibility and the Cover Catch
• KDP's Own Royalty Calculator vs Book Math Tools: What Each Covers
• Kindle's 70% Royalty Now Goes Up to $12.99: What to Reprice