Calculate the exact spine width for your Amazon KDP paperback. The spine width determines how wide the spine area of your cover needs to be, and it varies based on your page count and paper type.
Spine Width Formula
Amazon KDP uses two different paper stocks with different thicknesses:
| Paper Type | Thickness Per Page | Best For |
|---|---|---|
| White paper | 0.002252" (0.0572 mm) | Non-fiction, textbooks, books with images |
| Cream paper | 0.0025" (0.0635 mm) | Fiction, memoirs, poetry, literary works |
Formula: Spine Width = Page Count × Paper Thickness Per Page
For example, a 300-page book on cream paper: 300 × 0.0025" = 0.75" (19.05 mm)
Quick Reference Table
| Pages | White Paper Spine | Cream Paper Spine |
|---|---|---|
| 100 | 0.225" (5.7 mm) | 0.250" (6.4 mm) |
| 150 | 0.338" (8.6 mm) | 0.375" (9.5 mm) |
| 200 | 0.450" (11.4 mm) | 0.500" (12.7 mm) |
| 250 | 0.563" (14.3 mm) | 0.625" (15.9 mm) |
| 300 | 0.676" (17.2 mm) | 0.750" (19.1 mm) |
| 350 | 0.788" (20.0 mm) | 0.875" (22.2 mm) |
| 400 | 0.901" (22.9 mm) | 1.000" (25.4 mm) |
| 500 | 1.126" (28.6 mm) | 1.250" (31.8 mm) |
You might also need
- Margin Calculator
- Royalty Calculator
- KDP Cover Formatting Guide
- White vs Cream Paper
- KDP Trim Size Guide
Frequently asked questions
What is the spine width for a 300-page KDP book on cream paper?
A 300-page book on cream paper has a spine width of 0.75 inches (19.05 mm), calculated as 300 × 0.0025 inches per page.
Is cream paper thicker than white paper at KDP?
Yes. KDP cream paper is 0.0025 inches per page versus 0.002252 inches for white, so the same page count produces a slightly thicker spine on cream stock.
How many pages do I need before I can add spine text?
KDP requires a minimum spine width of 0.2 inches, which works out to roughly 79 pages on either paper type. Anything thinner has to ship with a blank spine.
Should I pick white or cream paper for a novel?
Cream paper is the standard for fiction, memoirs, and poetry because it reduces eye strain over long reading sessions. White paper is better for non-fiction, textbooks, and any book with images or colour content.
Need a professional book cover?
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Format my book →Further reading from official sources
- KDP — Paperback formatting & cover specs — Amazon's official spine formula.
