Free tool — private, in-browser, no signup
KDP manuscript checker
The formatting problems that ruin Kindle conversions are invisible in Word: tab indents, manual page breaks, blank-line spacing, chapter titles that aren’t real headings. Drop your .docx below and see them before KDP does.
Drop your .docx here
Checked instantly in your browser — the file is never uploaded, never stored, never read by anyone.
What we check, and why it matters
Tab and space indents. The single most common upload surprise. Word shows a tidy indent; Kindle shows chaos, because reflowable ebooks compute layout from paragraph settings, not typed characters. Authors routinely lose days re-fixing a 500-page manuscript after discovering this one paragraph at a time.
Manual page breaks and blank-line spacing. Both are layout-by-keystroke, and both fall apart when text reflows across screen sizes — stranded blank pages, vanished scene breaks, chapters starting mid-screen.
Heading styles.Kindle builds its table of contents and chapter navigation from Word’s Heading styles. No styles, no navigation — and it usually goes unnoticed until a reader complains.
Section breaks and images.Stray section breaks carry their own margins and page numbering into print; low-resolution images fail KDP’s print quality checks. We surface both so nothing ambushes you at upload.
Prefer to never think about this?
publish.ai takes your .docx exactly as it is, normalizes all of the above automatically, and delivers a validated EPUB, print-ready PDFs, designed covers, and your Amazon listing copy. One upload, minutes, from $29.99.
Common questions
Why do tab indents break Kindle books?＋
Kindle conversion treats a typed tab as literal content, not layout, so indents come out oversized, inconsistent, or missing depending on the device and font size. The fix is a real first-line indent: select all, then Paragraph → Indentation → Special: First line. One setting replaces every tab.
Are manual page breaks (Ctrl+Enter) bad for KDP?＋
They survive print better than ebooks. In a reflowable Kindle book, manual breaks strand blank pages and shift whenever the text reflows. The robust pattern is 'Page break before' on your Heading 1 style, so every chapter starts fresh without loose breaks in the text.
Why does my book need Heading styles?＋
Word's Heading styles are what conversion tools use to build the Kindle table of contents and chapter navigation. If your chapter titles are just bold text, the ebook ships without working navigation — one of the most common reasons a first upload looks broken.
Is my manuscript uploaded when I check it?＋
No. The checker unzips and scans your .docx entirely inside your browser using JavaScript. The file never leaves your computer, nothing is stored, and it works even if you go offline after the page loads.
Will fixing these issues guarantee KDP accepts my book?＋
These checks cover the classic Word-to-Kindle failure modes — indents, breaks, spacing, navigation — which cause most 'nothing fit right when I uploaded it' problems. Print adds its own requirements (margins, gutter, bleed, cover dimensions); see our KDP margins cheat sheet and cover calculator for those.