Cover · C-SPINE

Spine width differs from page count / paper calculation

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.

Error: Spine width differs from page count / paper calculation
Category: Cover
Severity: error
Auto Repair: Not automatic
Rule ID: C-SPINE
Affected: KDP=reject, Apple=unknown, Google=unknown, Kobo=unknown

Why this happens

• 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.

How platforms treat it

How Cermify detects it

1. Calculate expected spine width from page count and paper type.
2. Compare to uploaded spineWidthIn metadata or measured spine band.
3. Flag differences beyond tolerance as C-SPINE.
4. Note knock-on impact on full-wrap width (often with C-TRIM).

Automatic repair

Guided only. Moving spine artwork is design-sensitive; Cermify reports the target width and asks you to realign in the source tool.

Manual fix

1. Lock the final interior PDF page count and KDP paper type.
2. Recalculate spine width with KDP's formula/calculator.
3. Adjust the spine band and recenter spine title/author art.
4. Re-export the full wrap and recheck wrap width (C-TRIM).

Examples

Spine width must follow page count and paper type.

Incorrect

Configured spine: 0.40 in
Expected from page count/paper: 0.52 in

Correct

Spine band = 0.52 in matching calculator
Spine text centered in the updated band

FAQ

Can I keep an old spine if text still fits?

No—the fold positions move. Wrong spine width risks text wrapping onto the front/back covers.

Does cream paper change spine width?

Yes. Paper type is an input to KDP's spine calculation. Match the type you select in KDP.

Why isn't this auto-fixed?

Shifting spine art without a trustworthy preview can damage the design. Guided repair keeps visual control with you.

Related errors

• Full wrap size does not match trim + spine + bleed
• Text or critical art outside the safe zone
• Missing bleed or artwork does not reach bleed edge

References

• KDP spine width calculation
• Cermify cover engine — C-SPINE