How KDP calculates spine width
KDP multiplies your page count by a per-page thickness that depends on the interior and paper you choose:
Spine width = page count × paper factor
| Interior and paper | Inches per page | 300 pages |
|---|---|---|
| Black & white interior, white paper | 0.002252 | 0.676 in |
| Black & white interior, cream paper | 0.0025 | 0.750 in |
| Black & white interior, groundwood paper | 0.00235 | 0.705 in |
| Standard color interior, white paper * | 0.002252 | 0.676 in |
| Premium color interior, white paper | 0.002347 | 0.704 in |
* KDP’s pages disagree on standard color: the cover help page lists 0.002252 in per page, while the submission guidelines list a single “color paper” value of 0.002347 in per page. This calculator uses 0.002252. Confirm the spine with KDP’s own cover calculator before you finalize a standard color cover.
Full cover size
A KDP paperback cover is one PDF: back cover, spine and front cover side by side, with 0.125 in (3.2 mm) of bleed on every outside edge.
Width = 0.125 + trim width + spine + trim width + 0.125 in
Height = 0.125 + trim height + 0.125 in
Example: a 6 × 9 in book with 300 pages on white paper has a 0.676 in spine, so the cover is 12.926 × 9.25 in. Design images at 300 DPI or more.
Spine text, safe zone and barcode
- Spine text is allowed only on books with at least 80 pages (KDP’s wording: “more than 79 pages”). Keep it at least 0.0625 in (1.6 mm) from each fold, because the fold can shift by up to 0.0625 in either way.
- Safe zone: keep text and important images at least 0.125 in (3.2 mm) inside the trim lines. The template also keeps the same distance from the spine folds.
- Barcode: if you don’t supply one, KDP places a 2 × 1.2 in barcode in the lower right of the back cover. The template marks that corner so you can keep it clear.
- Before you upload, hide the template layer. KDP rejects covers that still contain guide lines or template text.
Hardcover, IngramSpark and Draft2Digital: coming soon
We only publish numbers we can verify. KDP doesn’t publish a spine formula for hardcovers, and IngramSpark and Draft2Digital don’t publish theirs either. Until we can confirm them, use each platform’s own tool:
- KDP hardcover: the cover calculator and template linked from KDP’s cover help pages.
- IngramSpark: the Cover Template Generator in your IngramSpark account (under My Tools). Remember that IngramSpark requires a barcode on every cover.
- Draft2Digital: D2D provides a cover template, or builds a wraparound cover from your front cover.
BoundReady will calculate all of these for you automatically once its numbers are verified.