For KDP paperback authors
Find the errors KDP will flag — before you upload
Most KDP rejections come from a short list of mechanical problems: wrong cover size, missing bleed, a spine that doesn't match your page count. Drop your files into the free checker and see exactly what KDP would object to — in about a minute.
Run the free pre-flight checkBrowse fix guidesThe free checker
Six checks on your real files — cover, interior, metadata, royalties, checklist — with a plain-language verdict for each.
Check my book →Fix guides by error
Got flagged already? Guides are organized by the exact message KDP showed you: what it means, why it happened, the fix.
Find my error →Spine & cover calculator
Spine width and full wraparound cover size from Amazon's published paper multipliers — inches, mm and 300 dpi pixels.
Calculate →How it works
Drop in your files. Cover PDF, interior PDF, or your metadata details — straight from your computer.
Checks run locally. Everything happens in your browser. Your manuscript is never uploaded or stored.
Fix and re-check. Each verdict tells you what to change. Re-run until it's clean, then upload with confidence.
Why a checker, not just a calculator?
Calculators do maths on numbers you type in. This checker measures your actual files — the real page boxes, the real spine, the real resolution — because that is what KDP measures. It grew out of a working verification service that checks manuscripts against real upload outcomes, including the failure patterns behind real rejections.
Your next upload could be the clean one
One avoided rejection saves days of re-uploads, dead launch momentum and support tickets. The check takes about a minute and costs nothing.
Start the free check