White vs cream paper and KDP spine width
KDP uses different spine factors for white and cream paper, so the same page count can produce a different spine width.
Use the numbers from your actual job
The guide explains the decision; the linked calculator gives you the value for your own file or production assumptions.
Use the provider-controlled final specification
Book dimensions depend on final page count, trim, paper/interior choice and current provider rules. Recalculate after any change that affects pagination or cover geometry.
Apply the answer to this specific question
KDP uses different spine factors for white and cream paper, so the same page count can produce a different spine width. The practical consequence should be checked with KDP Paperback Spine Width Calculator when your own dimensions, page count, cost or production values differ from the example implied by the question.
What commonly changes the result
For “White vs cream paper and KDP spine width”, the most important variables are the ones represented by the linked calculator and any provider-controlled specification. A correct arithmetic result can still be unsuitable if the source dimensions, category, page yield, trim, bleed, margin or production method were assumed incorrectly.
A better verification workflow
For White vs cream paper and KDP spine width, record the source measurement or controlling specification first, then run the real job values through kdp paperback spine width. Keep the result with the job notes, compare it with the physical file or material, and recheck any provider-controlled rule immediately before production or upload.
Practical answer
KDP uses different spine factors for white and cream paper, so the same page count can produce a different spine width.
When the decision affects a paid print run, book upload, client order or expensive material, keep the calculation with the job notes and verify any external specification again immediately before production.