Calculate the paperback spine width before laying out the cover.
Use the selected KDP paper stock and final interior page count to calculate paperback spine width and see whether spine text is allowed.
What does this tool check?
KDP paperback spine width is the final page count multiplied by the published paper-specific multiplier. KDP does not allow spine text below 79 pages.
Your calculated setup
- Spine width
- 0.27024 in
- Final even pages
- 120
- Spine text
- Allowed by page-count rule
Dimensions use the selected final interior page count and BoundHive KDP rules version. Recalculate after the exported interior PDF has its final page count.
Rules version 2026-09-07 · Amazon KDP cover requirements
Use these settings in a new bookInputs, calculation, and limits
- What you enter
- Ink and paper type and the final page count of the interior PDF, rounded up to an even number.
- How the number is calculated
- Spine width = final page count x paper factor. Amazon publishes the factor per paper type: 0.002252 in for white paper and standard color, 0.0025 in for cream paper, and 0.002347 in for premium color. Spine text is only printed on books with at least 79 pages.
- What the result cannot tell you
- The factor is a manufacturing average; leave clear space between spine text and the fold lines. Hardcover spines use a different table and are not covered here.
A 6 x 9 in paperback, black ink on white paper, 200 interior pages, no interior bleed (KDP rules version 2026-09-07):
- Spine width: 200 x 0.002252 in = 0.4504 in.
- Spine text is allowed because the book has at least 79 pages.
- The same book on cream paper would use 0.0025 in per page instead.
How wide does the full-wrap cover need to be, and how thick is the spine?
The cover width is back cover plus spine plus front cover plus bleed on both sides; the spine width is the final even page count multiplied by the paper-specific factor Amazon publishes, so the cover cannot be sized before the interior page count is final.
Prepare the cover in a book projectHow BoundHive keeps the answer reproducible
The calculator uses the same versioned specification catalog as Book Studio. It validates the complete option combination before returning a dimension and records the rules date with the result.
Amazon can change requirements. Recheck the final files against the current KDP previewer and official documentation immediately before submission.