The Three Main Ebook Formats
Every ebook you create will be delivered in one of three primary formats. Each has different strengths, and the right choice depends on your distribution platform and how readers will consume your content.
- PDF (Portable Document Format) - Fixed layout. The page looks exactly the same on every device. Best for print and direct distribution.
- EPUB (Electronic Publication) - Reflowable content. Text adapts to the reader's screen, font preferences, and accessibility needs. Best for ebook stores and reading apps.
- DOCX (Microsoft Word) - Editable document. Best for collaboration, editing, and platforms that require Word format input.
Most authors need at least two of these: EPUB for ebook platform distribution, and PDF for everything else. DOCX is useful if you collaborate with editors or need to polish content in Word before final export.
PDF: Fixed Layout
PDF is the most universally readable document format. Every computer, phone, and tablet can open a PDF without special software. What you design is exactly what the reader sees.
Strengths
- Pixel-perfect layout - Fonts, images, margins, and formatting are preserved exactly as designed.
- Universal compatibility - Opens on any device, any operating system, any browser.
- Print-ready - The same file you distribute digitally can be sent to a printer.
- Professional appearance - Supports custom fonts, decorative elements, page borders, headers, footers, and complex layouts.
- No conversion needed - What you export is the final product.
Weaknesses
- Not reflowable - Text does not adapt to screen size. On a phone, readers must zoom and scroll horizontally.
- Accessibility limitations - Readers cannot change font size or spacing in most PDF viewers.
- Not accepted for Kindle ebooks - Amazon does not properly convert PDF to reflowable Kindle format.
- Larger file sizes - Embedded fonts and high-resolution images increase file size.
Best for
- Lead magnets and free downloadable guides
- Print-on-demand (Amazon KDP Print, IngramSpark, Lulu)
- Course materials and workbooks
- Cookbooks and image-heavy content
- Direct sales from your website
- Email delivery to subscribers
EPUB: Reflowable Content
EPUB is the industry standard for digital books sold through ebook stores. It is essentially a structured package of HTML, CSS, and images - which means the content reflows to fit any screen.
Strengths
- Reflowable text - Content adapts to any screen size: phone, tablet, e-reader, desktop.
- Reader control - Readers can change font, font size, line spacing, margins, and background color.
- Accessibility - Supports screen readers, dyslexia-friendly fonts, and high-contrast modes.
- Small file size - Text-based content compresses efficiently, keeping delivery costs low.
- Industry standard - Accepted by Amazon KDP, Apple Books, Kobo, Google Play Books, Barnes & Noble, and all major ebook distributors.
- Table of contents navigation - Built-in TOC lets readers jump between chapters.
Weaknesses
- Layout variation - Your book will look different on different devices. You cannot control exact page layout.
- Image positioning - Images may appear at different sizes and positions depending on the reader's device and settings.
- Complex layouts are difficult - Tables, multi-column layouts, and precise image-text wrapping are hard to achieve consistently.
- Requires a reader app - Not all devices open EPUB natively (though most modern ones do).
Best for
- Amazon Kindle (converted to KPF/AZW during upload)
- Apple Books
- Kobo, Google Play Books, Barnes & Noble
- Smashwords, Draft2Digital, and other distributors
- Any text-first ebook where reader comfort matters most
DOCX: Editable Format
DOCX is not a final distribution format - it is a working format. Use it when you need to edit content in Word or Google Docs, share with collaborators, or upload to platforms that require Word documents.
Strengths
- Fully editable - Open in Word, Google Docs, or LibreOffice for further editing.
- Track changes - Editors can use Word's revision tools, making collaboration easy.
- Wide compatibility - Most platforms accept DOCX as an input format (including Amazon KDP).
- Familiar - Most people already know how to work with Word documents.
Weaknesses
- Not a final format - DOCX is not meant for direct distribution to readers.
- Formatting fragility - Styles can shift between different versions of Word, different operating systems, and different applications.
- Conversion required - Must be converted to PDF or EPUB for distribution.
- Limited design control - Custom decorative elements, precise positioning, and advanced typography are limited compared to PDF.
Best for
- Sharing with editors, proofreaders, or co-authors
- Uploading to platforms that process Word files (some publishers, Reedsy, etc.)
- Creating a master document you will convert to other formats later
- Quick text edits before final export in another format
Side-by-Side Comparison
| Feature | EPUB | DOCX | |
|---|---|---|---|
| Layout | Fixed | Reflowable | Semi-fixed |
| Reader can change font | No | Yes | Yes (editing) |
| Image quality control | Excellent | Good | Good |
| Amazon Kindle | Paperback only | Recommended | Accepted |
| Apple Books | Accepted | Recommended | Not accepted |
| Print-on-demand | Required | Not used | Not used |
| Lead magnets | Standard | Uncommon | Uncommon |
| Editable after export | Difficult | Difficult | Easy |
| File size | Larger | Smaller | Medium |
| Accessibility | Limited | Excellent | Good |
Which Format for Which Platform
- Amazon KDP (ebook): EPUB (recommended) or DOCX
- Amazon KDP (paperback): PDF (required)
- Apple Books: EPUB
- Google Play Books: EPUB (recommended) or PDF
- Kobo: EPUB
- Barnes & Noble (Nook): EPUB
- Smashwords / Draft2Digital: EPUB or DOCX
- IngramSpark (print): PDF
- Your website (direct sales): PDF (most common) or EPUB
- Email delivery (lead magnets): PDF
- Editors and collaborators: DOCX
Which Format for Which Use Case
Self-publishing a novel or non-fiction book
Export to EPUB for Kindle and other ebook stores. If you also want a paperback, export to PDF as well. Two files cover all distribution channels.
Creating a lead magnet
Export to PDF. Lead magnets are typically downloaded once, read on a computer or phone, and possibly printed. PDF preserves your branding and design perfectly.
Building a course or workbook
Export to PDF for distribution. If students need to fill in responses digitally, consider DOCX as an additional option. PDF preserves the designed layout of worksheets and exercises.
Selling on your own website
PDF is standard for direct website sales. If your audience uses dedicated e-readers, offer EPUB as an additional option. Some platforms like Gumroad and Payhip support delivering multiple formats per purchase.
Sharing with an editor
Export to DOCX. Your editor can use Word's Track Changes and Comments features to provide feedback directly in the document.
Wide distribution (multi-platform)
You need at minimum: EPUB for ebook stores and PDF for print/direct. DOCX as a working master is optional but useful if you plan to make ongoing edits.
Converting Between Formats
If you need to convert between formats, understand the quality trade-offs:
Good conversions
- EPUB to PDF - Works well. Layout becomes fixed. Tools: Calibre, Adobe InDesign, or any EPUB reader with print-to-PDF.
- DOCX to EPUB - Works well if the Word document uses proper heading styles. Tools: Calibre, Sigil, Kindle Create, or Inkfluence AI.
- DOCX to PDF - Works well. Save/export from Word or Google Docs.
Problematic conversions
- PDF to EPUB - Unreliable. PDF does not contain semantic structure (headings, paragraphs) in a way that converts cleanly to reflowable EPUB. Results often need significant manual cleanup.
- PDF to DOCX - Partial success. Simple text-heavy PDFs convert okay. PDFs with complex layouts, images, or custom fonts often break.
Best practice
Author your content in a tool that exports natively to all formats you need. Converting after the fact always risks formatting loss. Inkfluence AI exports directly to PDF, EPUB, and DOCX from the same source content, applying appropriate formatting for each output format.
Export Options in Inkfluence AI
When you export from Inkfluence AI, you have control over several formatting options that apply to all output formats:
- Table of contents - Auto-generated from chapter headings. Linked in PDF (clickable) and EPUB (navigation). Can be toggled on or off.
- Copyright page - Auto-generated with your name and year. Toggle on or off.
- Chapter numbering - Numeric (Chapter 1, 2, 3), Roman (Chapter I, II, III), or none.
- Decorative elements - Drop caps, section dividers, pull quotes, step badges, callout boxes, recipe cards, page borders, and chapter accents. Available across all formats.
- Header and footer - Custom text in the page header and/or footer (PDF).
- Page numbers - Toggle on or off (PDF).
- Branding - Paid users can remove the Inkfluence AI watermark and branding from exports.
Format availability by plan
- Free: PDF export with watermark
- Creator: PDF + EPUB, branding removable
- Premium: PDF + EPUB + DOCX, all features