KDP Spine Width Calculator
Enter your page count and paper type below to get the exact spine width Amazon uses for KDP paperbacks, calculated with the same formula this tool uses internally.
This is the spine width for your interior file. When you generate your actual cover template in KDP, use Amazon's own cover calculator for the final front+spine+back+bleed dimensions, it will use this same spine number.
Common questions
How do I calculate KDP spine width?
Multiply your page count by a per-page thickness factor: 0.002252″ for white paper, 0.0025″ for cream paper, or 0.002347″ for premium color paper.
Does spine width include the cover?
No, this is just the spine itself. Amazon's cover template tool adds this number between your front and back cover panels, plus bleed, when generating your final print-ready cover.
Why does paper type change the spine width?
Cream paper is physically thicker than white, and premium color paper is thicker still, so the same page count produces a different spine width depending on the paper you choose.
What happens if I get the spine width wrong?
Your cover text or artwork can end up misaligned with the printed spine, sometimes wrapping onto the front or back panel. Get this number right before you design the cover.
Why this matters
The spine width isn't just a formatting detail, it's the number your cover designer needs before they can lay out anything. Get it wrong and you'll find out after your proof copy arrives with text bleeding off the spine, or your title crammed into a space too narrow for it.
If you're formatting the interior yourself, KDP Workspace's free Interior Assembler calculates this automatically alongside your margins and gutter, so you're never guessing.
Try the free tool →