First-Party Data Study
PDF vs EPUB: How Authors Actually Export AI Books
We looked at the export format of 33,549 books created with Inkfluence AI. The result is lopsided: among authors who export, PDF wins by roughly 30 to 1 over EPUB. Here is the data, why it happens, and how to choose the right format for your book.
Quick Answer
Authors export AI books to PDF far more than any other format. Of the 41.5% of 33,549 books that were exported at least once, 92% chose PDF, 5% DOCX, and just 3% EPUB, meaning PDF is picked roughly 30 times more often than EPUB. PDF wins because it is print-ready, looks identical everywhere, and suits the fixed-layout non-fiction (guides, workbooks, cookbooks) that people write most. EPUB is still the right pick for reflowable reading and the Kindle store, just for a smaller slice of books. See PDF and EPUB export and how to choose a format.
The export format authors actually pick
Share of the 41.5% of books that were exported at least once, by last export format.
Figures are each book's most recent export format. A single book can be exported to more than one format over time; this measures where authors land.
Straight answers on ebook export formats
The questions authors ask most, answered from the data.
Do more authors export to PDF or EPUB?
PDF, overwhelmingly. In this study of 33,549 books, of the 41.5% that were exported, 92% landed on PDF versus just 3% on EPUB. Inkfluence AI supports both, but authors reach for PDF about 30 times more often.
Why is PDF so dominant?
Because most AI books are fixed-layout practical non-fiction, guides, workbooks, cookbooks, where the design is the product. PDF preserves that exact layout on any device and in print, and it is the easiest file to sell or hand to a reader directly.
When is EPUB the better choice?
For reflowable reading: novels, long-form non-fiction, and anything listed in the Kindle, Kobo, or Apple Books stores, which expect EPUB. It lets readers change font size and adapts to any screen. It is the right format for a smaller, specific slice of books.
What format does Amazon KDP need?
It depends what you publish. A Kindle ebook uploads best as EPUB; a KDP paperback uses a print-ready PDF interior. Many authors on Inkfluence AI export both from the same book, an EPUB for the store and a PDF for print and direct sales.
Why PDF wins by 30 to 1
EPUB is, on paper, the "proper" ebook format. It is the open industry standard, maintained by the W3C, and it reflows to any screen. So why do authors pick PDF almost 30 times more often? Because the export data and the genre data tell the same story.
The most common things people make with AI are practical, fixed-layout non-fiction: how-to guides, workbooks, cookbooks, planners, and lead magnets. For those, layout is the product. A workbook's worksheets, a cookbook's recipe cards, a planner's grid, none of them survive being reflowed. PDF preserves the exact design on every device and in print, which is precisely what those genres need.
PDF is also the path of least resistance for getting paid. You can attach it to an email, sell it on Gumroad or your own site, hand it out as a lead magnet, or drop it into a KDP or IngramSpark paperback as the print interior. No e-reader required, no conversion step, it just opens.
EPUB's strengths, reflowable text and adjustable font size, matter most for long-form reading: novels and narrative non-fiction meant to be read cover to cover on a Kindle or phone. That is a real and important use case; it is simply a smaller share of what people create with AI today.
The format follows the genre
Line the export data up against what people actually write and the pattern is obvious: the genres that dominate are the ones that need fixed layout, which is exactly why PDF dominates. Here is how the most common AI book types map to a format.
| Book type | Share of AI books | Natural format | Why |
|---|---|---|---|
| How-to & practical guides | 19.1% | Layout and design carry the value | |
| Fiction & novels | 15.3% | EPUB | Reflowable long-form reading |
| Self-help & personal development | 7.4% | Often sold direct or as a lead magnet | |
| Romance | 4.7% | EPUB | Read cover to cover on a Kindle |
| Cookbooks | 3.3% | Recipe layouts must stay intact | |
| Workbooks & planners | 3.1% | Worksheets and grids break if reflowed | |
| Children's books | 3% | Fixed illustrated pages |
The fixed-layout types, guides, self-help, cookbooks, workbooks, and children's books, add up to a large majority of AI books, and every one of them points at PDF. Fiction and romance, which suit EPUB, are a meaningful but smaller share. The export split is not a quirk of habit; it is what you would predict from what people are writing.
Which format should you export?
| If your book is... | Best format | Why |
|---|---|---|
| A workbook, planner, or cookbook | Fixed layout must stay intact | |
| A lead magnet or direct-sale guide | Opens anywhere, easy to deliver and sell | |
| A paperback (KDP / IngramSpark) | Print interiors are PDF | |
| A novel or long-form read | EPUB | Reflows and adjusts to any screen |
| A Kindle store ebook | EPUB | Amazon KDP prefers EPUB for Kindle |
| A draft to keep editing in Word | DOCX | Editable handoff to Word or a designer |
The honest takeaway: there is no single "right" format, only the right one for what you are publishing. Most AI books are practical and fixed-layout, so PDF fits the majority, which is exactly why the data leans so hard that way. If you are writing a novel or listing on Kindle, reach for EPUB. Many authors export both: a PDF to sell and print, and an EPUB for the stores. See the full export and publishing guide for the step-by-step.
How this squares with the wider ebook world
It is worth stressing that PDF's dominance here reflects what people make with AI, not that EPUB is second-rate. In the broader publishing world, EPUB is the reflowable standard for retail ebooks: Amazon KDP recommends EPUB for Kindle uploads, and Apple Books, Kobo, and Google Play are all EPUB-first. If your goal is a novel on Kindle, EPUB is simply correct.
What our data adds is the other half of the picture the store-centric view misses: a huge amount of real-world author activity happens outside the retail stores, direct sales, lead magnets, printed workbooks, PDFs handed to a client or a class. In that world, PDF is not a compromise; it is the best tool for the job, and it is where most finished AI books actually go.
Both facts are true at once. The store ecosystem is EPUB-first, and the majority of books people finish are PDF-first, because most people are publishing something practical and selling it directly. Knowing which world your book lives in tells you which format to export.
Sources: Amazon KDP supported formats, W3C EPUB 3 standard. Export figures are first-party data from Inkfluence AI.
Methodology
- Sample: 33,549 books created with Inkfluence AI, aggregated as of mid-2026 via a database-wide query. No individual books or authors are identified.
- What was measured: each book's most recent recorded export format. A book can be exported multiple times; we count where it last landed.
- Exported at least once: 41.5% of all books. The PDF / DOCX / EPUB shares in this study are of that exported group.
- Genre mapping: genre shares come from the same dataset (see the companion study, what people write with AI). Format-per-genre reflects the format best suited to each type, not a per-genre export measurement.
- Known limits: the metric captures the last format only, so a book exported to EPUB and later to PDF counts as PDF. Kindle-package and audiobook exports are tracked separately and are not included in this PDF/EPUB/DOCX split.
This is original, first-party data from Inkfluence AI. You are welcome to cite it with a link to this page.
Frequently Asked Questions
Do authors export ebooks as PDF or EPUB?
Why do most authors export to PDF instead of EPUB?
Is PDF or EPUB better for Amazon KDP?
What percentage of AI books get exported at all?
When should I use EPUB instead of PDF?
When should I use PDF?
What about DOCX exports?
Does the format an author picks reflect what they are writing?
How many books is this based on?
Can one book be exported to more than one format?
Which format is best for selling a book directly to readers?
What does this data tell a first-time author?
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