Guide
The best file format for AI narration, ranked
The same book can sound polished or patchy depending on the file you start from. Here is the ranking, and the quick fix that gets each format to its best.
1. EPUB (and KEPUB, AZW3, MOBI, FB2)
Ebook formats carry chapters, headings and reading order, so you get an accurate chapter list and the front matter is easy to skip. If you have the choice, start here.
Quick fix: usually none. If the whole book is one chapter, add headings in Calibre’s editor.
2. DOCX
Word’s heading styles become chapters and the text is clean. Headers, footers and comments are left out of the narration.
Quick fix: use Heading 1 for chapter titles, accept or reject tracked changes, and keep text out of floating boxes.
3. TXT, RTF, HTML
Plain text reads perfectly sentence by sentence; it only lacks structure. Lines such as “Chapter 3” or “# Part Two” become chapters, otherwise the text is split into even sections. HTML keeps its headings.
Quick fix: put chapter titles on their own line, add “Title:” and “Author:” lines at the top, and save as UTF-8.
4. PDF with a text layer
PDFs work well: page numbers and running headers are removed, hyphenated words rejoined and paragraphs stitched across pages. Chapters come from the PDF’s bookmarks or its headings. You can even follow along on the original page, with each word highlighted as it is read.
Quick fix: if you also have the EPUB or DOCX, use that. Otherwise export the PDF with bookmarks from the app that made it.
5. Scanned PDFs
A scan is a picture of a page. If it has a text layer (many scanner apps add one with OCR), it reads like any PDF. A scan with no text layer has nothing to read.
Quick fix: run OCR in your scanner app, or find a text edition.
A note on size
Files can be up to 10 MB. Text is tiny: a 100,000-word novel is under 1 MB as an EPUB. A bigger file is mostly pictures; remove them and the same book fits.
Questions people ask
Does the format change how the narrator sounds?
No. The voice is the same; the format decides what the narrator is given to read: structure, headings and any stray text.
Should I convert my PDF to EPUB first?
Only if you can get the real ebook. Converting a PDF in Calibre rarely beats dropping the PDF itself.
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