Independent publishing resource
KDP Spine Width Calculator
Spine width is a production measurement, not a visual guess. Calculate it only after the interior is final, then center spine artwork inside the safe region supplied for the edition.
Start a cover project
Cover measurement planner
Enter your working measurements in inches. This planning result does not replace the current production template for your exact marketplace, format, paper, and page count.
Planning result
Calculating…
Start with the final page count
The page count comes from the uploaded and processed interior, including front matter and intentional blanks. Updating the manuscript after cover design can make the existing spine inaccurate.
Apply the paper-specific factor
Spine width is generally page count multiplied by a paper-specific thickness factor. Because available stocks and formulas can change, verify the current factor for the marketplace, ink, and paper combination you selected.
Use spine text conservatively
Very thin books may not support readable spine text. When text is allowed, leave generous space from both folds and preview at full size rather than relying only on a zoomed-out mockup.
Frequently asked questions
Does trim size affect spine width?
Page count and paper thickness drive the width directly, while trim size influences the overall cover dimensions and the appearance of text on that spine.
When should I remove spine text?
Remove it when the publisher does not permit it for the page count or when the available safe region cannot hold the text clearly without crowding folds.