KDP Cover Size: How to Work Out a Full-Wrap Paperback Cover

A KDP paperback cover is not a front cover. It is one flat image that wraps around the whole book: back cover, spine and front cover side by side, with a little extra all round for trimming. Get the size wrong and KDP rejects the file; get the spine wrong and your title ends up on the front. Here is how to work it out.

In short: cover width = bleed + trim width + spine + trim width + bleed, and cover height = trim height + 2 × bleed, where bleed is 0.125 inches. Spine width = page count × paper thickness (0.002252 in for white, 0.0025 in for cream, 0.002347 in for colour). The free spine width calculator does the sum and gives the pixel size at 300 DPI.

The parts of a full-wrap cover

From left to right, laid flat:

1. Bleed — 0.125 in that is trimmed off. Your background runs into it so no white edge shows.
2. Back cover — the same width as your trim size. The barcode goes at the bottom right, next to the spine.
3. Spine — its width depends on page count and paper.
4. Front cover — again the trim width.
5. Bleed — another 0.125 in on the right, plus 0.125 in at the top and bottom.

The formula

width = 0.125 + trim width + spine + trim width + 0.125

height = 0.125 + trim height + 0.125

And the spine:

spine = page count × paper thickness

Use the final page count of the printed interior, including blank pages and answer pages. If you add pages later, the spine — and the whole cover — changes.

Worked examples

The 8.5 × 11 in, 100-page row is the common size for coloring books and activity books. Get your own numbers from the spine width calculator — choose paper, trim and page count and it shows the spine, the full cover size and the pixels.

Spine text: when can you add it?

KDP only prints text on the spine of books with more than 79 pages. Thinner spines are too narrow to place text reliably, so leave them blank or use a solid colour. When you do add text, keep it at least 0.0625 in from each side of the spine, because the fold can move slightly in printing.

Safe zones on the cover

• Keep titles, author name and anything important at least 0.125 in inside the trim line on all sides. Only background should run into the bleed.
• Leave the barcode area at the bottom right of the back cover clear, or place your own barcode there. See ISBN barcodes for KDP paperbacks, or make one with the free ISBN barcode generator.
• Export at 300 DPI as a PDF, with fonts embedded or converted to outlines.

Use KDP's template to check

KDP's own cover calculator gives a template for your exact trim size, page count and paper. Lay it over your design as a check: the spine guides, the barcode box and the safe areas should line up with your file. If the template and your numbers disagree, re-check the page count you entered — it is the most common cause.

Common cover size mistakes

• Front cover only. KDP paperbacks need the full wrap; a single front image is rejected.
• Wrong page count. The spine was worked out for the draft, then pages were added.
• No bleed. A cover made at exactly the trim size leaves white slivers after trimming.
• Text on a thin spine. Below 80 pages, spine text is likely to wrap onto the cover.
• Low resolution. A cover exported at 72 DPI looks soft in print. Use 300 DPI.

Before you upload

Cover size is tied to page count, which also sets your printing cost. Check what your book will cost to print in how much KDP charges to print a paperback, and choose a list price with the royalty calculator. For margins inside the book, see the trim size and margin guide.