Find your KDP paperback spine width in inches and millimeters from page count and paper type. Free, no sign-up.
How to use the KDP paperback spine width calculator
- Enter your final page count, as KDP counts printed pages.
- Choose your paper and ink type.
- Read the spine width in inches and millimeters, then use it in your cover file.
How KDP paperback spine width is calculated
Spine width equals your page count multiplied by the thickness of one page. The thickness depends on the paper and ink you choose when you set up your paperback:
| Paper and ink | Thickness per page |
|---|---|
| Black & white, white paper | 0.002252 in |
| Black & white, cream paper | 0.0025 in |
| Standard color | 0.002252 in |
| Premium color | 0.002347 in |
Here are three worked examples:
| Book | Paper | Calculation | Spine width |
|---|---|---|---|
| 200 pages | Black & white, white paper | 200 × 0.002252 = 0.4504 in | 11.44 mm |
| 200 pages | Black & white, cream paper | 200 × 0.0025 = 0.5000 in | 12.70 mm |
| 300 pages | Premium color | 300 × 0.002347 = 0.7041 in | 17.88 mm |
Spine text and the 79-page rule
KDP supports spine text only on books with 79 pages or more. Thinner books should leave the spine blank. When you do add spine text, keep it centered with a small margin on each side, so it does not drift onto the front or back cover.
Why the right spine width matters
If the spine in your cover file is too wide or too narrow, your artwork and text will sit in the wrong place after printing. Text can wrap onto the front or back cover, and covers that do not match KDP’s specifications can cause problems at approval. Because the spine changes with every page you add or remove, recalculate it whenever your page count changes.
Checklist before you upload your cover
- Your page count is final, including front and back matter.
- You chose the same paper and ink type in the calculator and in KDP.
- The cover file uses the spine width you calculated.
- You checked the result against KDP’s official cover template.
Frequently asked questions
Is a page the same as a sheet?
No. Page count means printed pages, which are both sides of a sheet, as KDP counts them.
Does this work for hardcovers?
No. These values are for paperbacks. Check KDP’s hardcover guidelines separately.
Why does KDP’s template show a slightly different spine?
KDP’s template uses its own rounding and is the official source. Use this calculator for planning and the KDP template for your final file.
Does the spine change if I switch paper?
Yes. Cream paper is thicker than white paper, so the same page count gives a wider spine.
More free KDP tools
All KDP tools
KDP Royalty Calculator
KDP Cover Size Calculator
Word Count to Page Count Converter
Amazon BSR to Sales Estimator
Need a cover that fits perfectly?
We design Amazon-ready covers for ebook, paperback and hardcover, with the correct spine and bleed.
Chat on WhatsAppSee our servicesEstimates only. Always confirm figures in your KDP dashboard and the KDP Help Center. Last updated: October 2026. See our Disclaimer.