Enter your trim size, paper type and page count. You get the exact spine width and full cover size for a KDP paperback, plus a 300 DPI template you can download and design over.
Cover done? Your press kit is next.
The Author Media Kit gives you 5 pre-written, editable pages (bio, book sheet, interview Q&A and more) for pitching podcasts, bloggers and bookstores. Works in Google Slides and PowerPoint.
How KDP calculates spine width
Amazon KDP works out spine width from two things: how many pages your book has and what paper it is printed on. Each paper type has a fixed thickness per page:
| Interior type | Per page | Page range (5″x8″ to 6″x9″) |
|---|---|---|
| Black & white, white paper | 0.002252″ (0.0572 mm) | 24–828 |
| Black & white, cream paper | 0.0025″ (0.0635 mm) | 24–776 |
| Standard color, white paper | 0.002252″ (0.0572 mm) | 72–600 |
| Premium color, white paper | 0.002347″ (0.0596 mm) | 24–828 |
For example, a 300-page novel on cream paper has a spine of 300 × 0.0025 = 0.75 inches. The same book on white paper comes out at 0.676 inches, because white paper is thinner.
Full cover size formula
A paperback cover is uploaded as one PDF with the back cover, spine and front cover side by side. KDP needs an extra 0.125″ (3.2 mm) of bleed on every outside edge:
- Width = 0.125″ + trim width + spine width + trim width + 0.125″
- Height = 0.125″ + trim height + 0.125″
Say you have a 6″ x 9″ book with 300 cream pages. The full cover is 0.125 + 6 + 0.75 + 6 + 0.125 = 13″ wide and 9.25″ tall, which is 3900 × 2775 pixels at 300 DPI.
Cover design tips that prevent rejections
- Extend the background into the bleed. Anything in the bleed is trimmed off, but a design that stops at the trim line can leave a thin white edge.
- Keep text inside the safe zone. Leave at least 0.125″ between important text and the trim line. On the spine, keep 0.0625″ on each side because the fold can move slightly.
- Spine text needs 79+ pages. Below that, KDP won’t allow text on the spine because the spine is too narrow to print it reliably.
- Leave room for the barcode. KDP places a barcode near the bottom right of the back cover. Keep that area clear. The template marks it as a rough guide.
- Export at 300 DPI as a single PDF, with fonts embedded and text no smaller than 7 pt.
- Recalculate when your page count changes. Adding a new chapter or acknowledgments changes the spine width, so you’ll need to update the cover.
Always check your final numbers against KDP’s own cover calculator and previewer before you publish. Printing specs can change, and KDP’s previewer has the final say.
Frequently asked questions
Is this calculator accurate for Amazon KDP?
Yes. It uses the per-page paper thickness and 0.125″ bleed published in KDP’s paperback cover guidelines. The previewer is still the final check before you publish, so always upload a proof.
What is the ideal size for a Kindle ebook cover?
Ebook covers have no spine and no bleed. The commonly recommended size is 2560 × 1600 pixels (a 1.6:1 height-to-width ratio), saved as a JPG.
Does this work for hardcover books?
No, this calculator covers paperbacks only. Hardcover covers have a wraparound and hinge area, so their measurements are different. Use KDP’s hardcover cover calculator for case-laminate books.
How do I use the downloaded template?
Open the PNG in Canva, Photoshop, Affinity or any design tool and put it on the bottom layer. Design your cover over it, then hide or delete the template layer before you export your final PDF.
Can I put text on the spine of a thin book?
KDP requires at least 79 pages for spine text. With fewer pages, leave the spine blank or use a solid color or simple pattern.