The exact numbers
KDP cover size and spine width, calculated
The formula
- spine = page count × paper thickness
- width = (2 × trim width) + spine + 0.25" (0.125" bleed each outer edge)
- height = trim height + 0.25"
- pixels = inches × 300
Spine thickness per page
Multiply your page count by the number for your paper and ink:
| Paper & ink | Inches / page |
|---|---|
| Black ink · white paper | 0.002252" |
| Black ink · cream paper | 0.0025" |
| Black ink · groundwood paper | 0.00235" |
| Premium color · white paper | 0.002347" |
| Standard color · white paper | 0.002252" |
Spine width by page count
Black ink on white paper, the most common low-content setup:
| Pages | Spine width | At 300 DPI |
|---|---|---|
| 24 | 0.054" | 16 px |
| 50 | 0.113" | 34 px |
| 100 | 0.225" | 68 px |
| 120 | 0.27" | 81 px |
| 200 | 0.45" | 135 px |
| 300 | 0.676" | 203 px |
Spine text needs 79+ pages — below that, KDP prints the spine blank.
Full-cover size by trim
For a 120-page book, black ink on white paper. Change the page count and your spine — and the width — change with it:
| Trim | Full cover (in) | Pixels @ 300 DPI |
|---|---|---|
| 5 × 8" | 10.52 × 8.25 | 3156 × 2475 |
| 5.5 × 8.5" | 11.52 × 8.75 | 3456 × 2625 |
| 6 × 9" | 12.52 × 9.25 | 3756 × 2775 |
| 7 × 10" | 14.52 × 10.25 | 4356 × 3075 |
| 8.5 × 11" | 17.52 × 11.25 | 5256 × 3375 |
Get the exact size for your book
Enter your trim size, page count and paper. Get the exact full-cover size KDP needs and a correctly-sized template, before you upload. No login, no subscription.
Common questions
What size should my KDP cover be?
The full cover is wider than the book because it includes the back, the spine, and bleed. Width = (2 × trim width) + spine width + 0.25", and height = trim height + 0.25". For a 120-page 6×9 book on white paper that's 12.52" × 9.25", which is 3756 × 2775 pixels at 300 DPI.
How do I calculate KDP spine width?
Spine width = page count × paper thickness. Black ink on white paper is 0.002252" per page, cream is 0.0025", and premium color is 0.002347". So a 120-page black-and-white book on white paper has a spine of 120 × 0.002252 = 0.27".
How much bleed does a KDP cover need?
0.125" of bleed on every outside edge — top, bottom, and the outer sides. That's why the full-cover height is trim height + 0.25" (0.125" top + 0.125" bottom) and the width includes another 0.25" across the two outer edges.
What DPI does KDP require for a cover?
300 DPI minimum, with 600 DPI as the recommended maximum (higher resolutions can time out or bloat the file). Convert inches to pixels by multiplying by 300, so a 12.52" wide cover is 3756 pixels wide.
Do I need CMYK or RGB for a KDP print cover?
CMYK for print. RGB is for eBook covers. Spot colors aren't supported and should be converted to CMYK, and embedded fonts are required in the PDF.
Numbers verified against Amazon KDP's Create a Paperback Cover page and live Cover Calculator. Updated for KDP's 2026 spec.