Free tool
Book Spine Width Calculator
Calculate your paperback's spine width and full wrap cover size from the page count and paper type, to KDP's specification. Free, no sign-up.
A wraparound cover cannot be designed until the interior is final, because the spine is page count times paper thickness — one extra page changes the width, and a spine that is wrong by a millimetre wraps the artwork around the edge of the book.
Cream paper is thicker than white, so the same manuscript gives a wider spine on cream. Below 79 pages Amazon will not print text on the spine at all, because there is not enough of it to print on.
Common questions
- How do I calculate spine width for KDP?
- Multiply the page count by the paper thickness: 0.002252 inches a page for white paper, 0.0025 for cream. A 300-page cream paperback has a spine of 0.75 inches.
- What size should my full cover file be?
- Two covers plus the spine, plus 0.125 inches of bleed on all four sides. The figure above is the full wrap size for the trim and page count you entered — design to that, not to the trim size alone.
- Why does cream paper give a wider spine?
- It is physically thicker — 0.0025 inches a sheet against 0.002252 for white. Over 300 pages that is about a fifteenth of an inch, which is more than enough to misalign a cover designed for the wrong stock.
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