KDP Spine Width Calculator
Your cover template needs the spine width to the fraction of a millimeter. Enter your page count and paper type to get the exact KDP figure in inches and mm.
KDP formula: pages × 0.002252 in (white), × 0.0025 (cream), × 0.002347 (color). Use the exact figure in your cover template — a spine off by a millimeter shifts the whole cover.
Now format the book itself
These numbers all depend on your final typeset page count. PaperbackKit turns your Word manuscript into a KDP-ready 6×9 print PDF plus an accessible EPUB in about 5 minutes — so you get the real page count, not an estimate.
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Word manuscripts up to 15MB · your file is deleted after processing
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Frequently asked questions
What's the KDP spine width formula?
Page count × 0.002252 inches for white paper, × 0.0025 for cream, × 0.002347 for color paper. A 300-page book on cream paper has a 0.75-inch (19 mm) spine.
Why does my cover get rejected over the spine?
If the cover PDF's spine area doesn't match the computed width for your final page count, text drifts onto the front or back panels. Fix the page count first, then the cover — never the other way round.
When can I put text on the spine?
KDP requires roughly 79+ pages before spine text is allowed, and recommends leaving a small safety margin on both sides. Below that, keep the spine blank.
My page count isn't final yet — what should I do?
Typeset the interior first: the final PDF fixes your page count, which fixes your spine. PaperbackKit produces the finished KDP-ready interior from your Word file in minutes, so the cover designer gets a number that won't change.