Knowledge · Rule
Spine width differs from page count / paper calculation
Cover · C-SPINE
Definition
The spine band width on your cover does not match the width calculated from final page count and paper type, so spine text and folds can misalign.
Why
- Interior page count changed after the cover was designed.
- Wrong paper type (white vs cream) used in the spine formula.
- Manual spine guide drawn by eye instead of KDP's calculated width.
- Template from a different trim size reused without recalculating spine.
Impact
May block submission on KDP when this rule fails.
Platforms
| Platform | Result |
|---|---|
| KDP | May reject |
| Apple Books | Unknown |
| Google Play | Unknown |
| Kobo | Unknown |
References
- KDP spine width calculation
- Cermify cover engine — C-SPINE
Last updated · 2026-08-03
Why we believe
Provenance is loaded from RID (same source as Rule Radar) — not a second copy.
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