What This Guide Covers

Most ebook conversion advice is about why you should have an ebook. This guide is about how ebooks are actually built — what happens to your print-formatted file when it is converted to a reflowable digital format, what breaks during that conversion, how to fix it, and what each retailer requires for a file that passes ingestion without errors.

If you are an author, publisher, or production manager preparing an ebook edition alongside or after a print run, this guide covers the technical reality of conversion: format specifications, content that does and does not survive reflowing, image handling, metadata requirements, validation, and the platform-specific rules that determine whether your file is accepted or rejected at upload.

How Ebooks Differ From Print — The Core Concept

A printed book has fixed pages. The text, images, margins, and page breaks are locked to a specific trim size. What the designer laid out is what every reader sees.

An ebook has no fixed pages. The text reflows to fit whatever screen the reader is using — a 6-inch Kindle, a 10-inch iPad, a 5-inch phone. The reader controls font size, font choice, line spacing, and margins. Page numbers are meaningless (replaced by location markers or percentage). The “page” is a temporary rendering that changes every time the reader adjusts a setting or rotates the device.

This is the fundamental shift that drives every conversion decision: content that depends on fixed positioning — specific page breaks, precise image placement, multi-column layouts, text wrapping around images, exact margin measurements — does not transfer directly to a reflowable format. It must be restructured, approximated, or in some cases removed.

Ebook Formats: What Each One Is and Where It Goes

EPUB 3

EPUB is the open standard for reflowable ebooks, maintained by the W3C. EPUB 3 is the current version and is essentially a packaged website — HTML5 content, CSS3 styling, and metadata wrapped in a ZIP container with an .epub extension.

EPUB 3 is accepted by Apple Books, Kobo, Barnes & Noble (Nook), Google Play Books, and most other non-Amazon retailers. It supports reflowable text, embedded fonts (with DRM-compatible font obfuscation), embedded audio and video, MathML for equations, SVG for scalable graphics, and accessibility features including semantic markup and ARIA roles.

EPUB is the format you should produce first. It is the master from which other formats can be derived, and it is the format with the broadest retail acceptance.

KPF (Kindle Package Format)

Amazon’s Kindle ecosystem uses KPF as its preferred submission format. KPF files are produced using Amazon’s free Kindle Create tool from a Word document or EPUB source. Amazon also accepts EPUB and DOC/DOCX directly through Kindle Direct Publishing (KDP), and converts them internally — but the internal conversion sometimes produces unexpected results, especially with complex formatting.

The old MOBI/KF8 format is deprecated for new submissions. Amazon now converts all uploads to their internal KPF rendering. If you submit a clean EPUB, Amazon’s conversion is generally reliable for straightforward text-dominant books. For books with complex formatting, submitting a KPF file built in Kindle Create gives you more control over the output.

Fixed-Layout EPUB and KPF

For books where the visual layout is the content — children’s picture books, graphic novels, cookbooks with integrated text and photography, highly designed art books — a reflowable format destroys the work. Fixed-layout ebooks preserve the page design as a series of fixed-dimension screens, similar to a PDF but with ebook metadata and DRM compatibility.

Fixed-layout files are significantly larger than reflowable files (because each page is essentially an image or a complex HTML layout), they do not allow the reader to change font size or reflow text, and they display poorly on small screens. They are appropriate only for content that cannot function as reflowable text.

PDF

PDF is not a recommended ebook retail format. PDFs do not reflow, do not integrate with retailer DRM systems, and display poorly on small screens. Some direct-sales platforms (Gumroad, Payhip, author websites) distribute PDFs, and PDFs are common for academic and technical documents sold directly. But for retail ebook distribution through Amazon, Apple, Kobo, or B&N, PDF is not an option.

What Breaks During Conversion — And How to Handle It

Converting a print layout to a reflowable ebook is not an export operation. It is a reconstruction. The following elements require specific attention because they do not survive a straight format conversion.

Page Breaks and Chapter Starts

In print, chapters start on specific pages (often recto). In a reflowable ebook, there are no pages — chapters start wherever the previous chapter ends, unless you insert explicit chapter breaks in the EPUB markup. Every chapter must begin with a forced page break in the ebook file. This is handled through CSS (page-break-before: always) or through the EPUB’s spine structure.

If your print file uses blank pages to force recto starts, those blanks must be removed during conversion. A blank “page” in an ebook displays as empty screen space and confuses the reader.

Running Headers and Footers

Print books use running headers (book title, chapter title, author name) and page-number footers. Ebooks have neither. These elements must be stripped entirely during conversion. If running headers are accidentally left in the ebook file, they appear as orphaned text lines at the top of every chapter.

Footnotes and Endnotes

Print footnotes sit at the bottom of the page where they are referenced. Ebooks have no fixed page, so footnotes must be converted to either:

Pop-up notes — supported by most modern readers (Kindle, Apple Books, Kobo). The reader taps the superscript note number and a pop-up displays the note text. This is the preferred approach for most books.
Linked endnotes — the note number is a hyperlink that jumps to an endnote section at the back of the book, with a return link back to the reference point. This works on all devices but is less convenient for the reader.

Both approaches require restructuring the note content and adding hyperlink markup. A straight conversion from a print-formatted Word file or PDF will not produce functional notes — they will appear as inline text or broken references.

Images

Print images are embedded at 300 DPI in CMYK. Ebook images should be RGB, 72–150 DPI (higher resolution adds file size without visible benefit on screen), and optimized for file size. EPUB retailers impose file size limits — Amazon recommends keeping the total EPUB under 650 MB but charges a “delivery fee” per megabyte on certain royalty options, which means large image-heavy files directly reduce your royalty.

Images in reflowable ebooks cannot be precisely positioned relative to text the way they can in a print layout. An image that sits in the upper-right corner of a print page with text wrapping around it will, in a reflowable ebook, need to be placed as a block element — centered, full-width, with text above and below but not beside it. Complex text-and-image layouts must be simplified.

Image captions must be explicitly associated with their images in the markup, not positioned by proximity as they might be in a print layout.

Tables

Simple tables (a few columns, short cell content) convert reasonably well to EPUB, though they may require horizontal scrolling on small screens. Complex tables — wide tables with many columns, tables with merged cells, tables with extensive text in cells — often do not render legibly on small devices.

Options for handling complex tables in ebooks:

Simplify the table to fewer columns
Convert the table to a list format
Render the table as an image (sacrifices accessibility and text searchability)
Use a fixed-layout page for that specific table within an otherwise reflowable book (a hybrid approach supported by EPUB 3 but not universally rendered well)

Drop Caps and Ornamental Typography

Print drop caps (large initial letters spanning multiple lines) are inconsistently supported across ebook readers. Some readers render CSS drop caps correctly; others ignore the styling entirely, leaving a lone capital letter on its own line. If your design uses drop caps, test the ebook on multiple devices and accept that the rendering will vary.

Ornamental section breaks (dingbats, fleurons, decorative rules) should be converted to small inline images rather than relying on special characters, which may not be available in the reader’s font.

Margins, Indentation, and Spacing

Print layouts use precise point-based margins and indentation. Ebook CSS should use relative units (em, %) rather than fixed units (pt, px) so that spacing scales proportionally when the reader changes font size. A first-line indent of 0.3 inches in print becomes text-indent: 1.5em in the ebook CSS.

Paragraph spacing (space before/after) should also use relative units. Excessive spacing that looks correct on a large tablet can consume most of the screen on a phone.

Hyperlinks and Cross-References

Print books reference page numbers (“see page 142”). Ebooks have no stable page numbers. All internal cross-references must be converted to hyperlinks pointing to the relevant chapter, section, or note anchor. External URLs should be live, tappable hyperlinks.

A table of contents in the ebook must be both a navigable HTML document (the “NCX” or “nav” document in the EPUB structure) and optionally an inline HTML page that the reader can access. Most retailers require a functional navigation TOC as part of the EPUB package.

Metadata: What the Retailer Needs Beyond the File

An ebook file contains embedded metadata, and each retailer requires additional metadata at upload. Getting metadata wrong does not break the file, but it can prevent discovery, misclassify the book, or cause the listing to be rejected.

Required Metadata (All Platforms)

Title — must match the print edition exactly if this is a companion ebook
Author name(s) — as they should appear on the retail listing
ISBN — a separate ISBN from the print edition (each format gets its own ISBN if you are using ISBNs; Amazon does not require an ISBN for Kindle-exclusive titles, but other retailers generally do)
Language — ISO 639-1 code (e.g., “en” for English)
Publisher name — if self-publishing, this is your imprint name or your own name
Publication date
Description / synopsis — retailer product listing copy
BISAC subject codes — category classifications that determine where the book appears in retailer browse categories (up to three codes on most platforms)
Cover image — a high-resolution JPEG or PNG for the retail listing (minimum dimensions vary by retailer; Amazon requires at least 1000px on the longest side, recommends 2560px)

Platform-Specific Requirements

Amazon KDP — accepts EPUB, DOC/DOCX, or KPF. Requires a KDP account. Offers two royalty options (35% and 70%) with different pricing and territory rules. The 70% option includes a per-megabyte delivery fee, which matters for image-heavy books. Amazon does not require an ISBN but assigns an ASIN (Amazon Standard Identification Number) to every Kindle title.

Apple Books — accepts EPUB 3. Submission through Apple Books for Authors (formerly iTunes Connect) or through an aggregator. Requires an ISBN. Apple imposes strict EPUB validation — files must pass epubcheck without errors.

Kobo — accepts EPUB. Submission through Kobo Writing Life or an aggregator. Requires an ISBN for most territories.

Barnes & Noble (Nook) — accepts EPUB. Submission through B&N Press. Requires an ISBN.

Google Play Books — accepts EPUB or PDF. Submission through Google Play Books Partner Center. Requires an ISBN.

Aggregators vs. Direct Upload

You can submit your ebook directly to each retailer, or use an aggregator (Draft2Digital, PublishDrive, StreetLib) that distributes to multiple platforms from a single upload. Aggregators simplify distribution but take a percentage of royalties and add a layer between you and each retailer’s reporting and pricing controls. Direct upload gives you full control but requires maintaining accounts and files on each platform separately.

For more on ISBNs and format-specific registration, see our ISBN guide. For distribution strategy, see our book distribution guide.

The Conversion Process: How We Build an Ebook

Step 1: Source File Assessment

We start with whatever file you have — typically an InDesign package, a print-ready PDF, or a Word document. We assess the content for conversion complexity: how many images, whether there are footnotes, tables, special typography, or complex layouts that require restructuring for reflow.

Simple text-dominant books (novels, memoirs, essays, poetry collections without visual elements) are straightforward conversions. Image-heavy or layout-complex books (cookbooks, textbooks, design books, children’s books) require more restructuring and may warrant a fixed-layout approach for some or all pages.

Step 2: Content Extraction and Restructuring

We extract the text and images from the source file, strip print-only elements (running headers, page numbers, blank recto-forcing pages), and restructure the content for reflowable output. This includes:

Building a semantic HTML structure (headings, paragraphs, lists, blockquotes)
Converting footnotes to pop-up notes or linked endnotes
Replacing page-number cross-references with hyperlinks
Resizing and optimizing images for screen (RGB, 72–150 DPI, compressed)
Simplifying or rebuilding tables
Building the navigation table of contents

Step 3: Styling and Testing

We apply CSS styling to match the intent of the print design within the constraints of reflowable rendering — heading fonts, body text indentation, spacing, image sizing, and chapter-break behavior. We test the EPUB across multiple rendering engines:

Apple Books (macOS and iOS) — WebKit-based, generally the most capable renderer
Kindle Previewer — Amazon’s official emulator for Kindle devices and apps
Adobe Digital Editions — reference EPUB reader used for validation
Kobo Desktop — Kobo’s rendering engine
Thorium Reader — open-source EPUB 3 reader useful for accessibility testing

Each reader renders CSS slightly differently. We verify that the ebook reads correctly and looks acceptable across the major platforms, not just one.

Step 4: Validation

Every EPUB we produce is run through epubcheck, the official EPUB validation tool maintained by the W3C. Epubcheck verifies structural integrity, metadata completeness, internal link validity, image references, and compliance with the EPUB specification. A file that passes epubcheck will be accepted by every retailer that accepts EPUB.

For Kindle, we additionally validate the file in Kindle Previewer to catch any Amazon-specific rendering issues before upload.

Step 5: Delivery

We deliver:

A validated EPUB 3 file for non-Amazon retailers
A KPF or Amazon-optimized EPUB for Kindle (if requested)
A cover image file at retailer-recommended resolution
A metadata summary sheet with all required fields populated

If you are distributing directly to retailers, you upload these files yourself. If you use an aggregator, you upload the EPUB and metadata to the aggregator’s dashboard.

What Converts Cleanly and What Requires Work

Content Type	Conversion Complexity	Notes
Prose chapters (novels, memoir, essays)	Low	Straightforward reflow; minimal restructuring
Poetry with standard formatting	Low–Medium	Line breaks and stanza spacing must be explicitly preserved in markup
Footnotes / endnotes	Medium	Must be rebuilt as pop-up notes or linked endnotes
Simple tables (2–4 columns)	Medium	May need simplification for small screens
Images with captions	Medium	Repositioned as block elements; captions linked in markup
Complex tables (5+ columns, merged cells)	High	Often converted to images or restructured as lists
Sidebars and callout boxes	High	Rebuilt as styled blocks; positioning is approximate
Text wrapping around images	High	Wrap removed; images become block-level centered elements
Multi-column layouts	High	Columns collapsed to single flow
Mathematical equations	High	Requires MathML or image rendering
Full-page illustrations with integrated text	Very High	May require fixed-layout pages
Interactive elements (audio, video)	Very High	Supported by EPUB 3 spec but inconsistently by readers

Common Ebook Conversion Errors

Exporting directly from InDesign or Word to EPUB without restructuring. Automated exports preserve print formatting artifacts that break in reflow — fixed positioning, absolute-unit spacing, non-semantic markup. A clean ebook requires manual restructuring, not just a file format change.
Leaving print-only elements in the file. Running headers, page-number references, blank pages, and “Continued on next page” lines must be removed. They make no sense in a reflowable context and signal an amateur conversion.
Using the print cover file as the ebook cover. The print cover is a full wrap (front, spine, back) in CMYK at 300 DPI. The ebook cover is the front panel only, in RGB, cropped to the front cover dimensions, and exported at retailer-specified resolution. Submitting the full print wrap as an ebook cover results in a tiny, unreadable thumbnail showing spine and back cover.
Not testing on multiple devices. An ebook that looks correct in Apple Books may have rendering issues in Kindle or Kobo. Test on at least three platforms before distribution.
Submitting an EPUB that fails epubcheck. Retailers run validation on upload. A file with epubcheck errors may be rejected outright or may render incorrectly on some devices. Always validate before submission.
Using fixed-unit CSS (pt, px) instead of relative units (em, %). Fixed units do not scale with reader font-size preferences. A 12pt font-size declaration in CSS is ignored by most readers, but fixed margins and indentation values cause layout problems.
Forgetting that ebooks need a separate ISBN. An EPUB is a different format from the print edition and requires its own ISBN if you intend to distribute through standard retail channels. Using the print ISBN on the ebook creates catalog confusion.
Oversized image files inflating the EPUB. A 300 DPI CMYK TIFF from the print file has no place in an ebook. Convert to RGB JPEG or PNG at 72–150 DPI and compress. Large file sizes increase Amazon’s delivery fee and slow download times on mobile networks.
No navigation TOC. Every EPUB must include a machine-readable navigation document (the nav element in EPUB 3). Without it, the reader’s built-in table of contents is empty, and the file may fail validation.
Broken internal links. Cross-references that pointed to page numbers in print must be converted to hyperlinked anchors. A reference to “see Chapter 7” should jump to the Chapter 7 heading, not display a dead page number.

Ebook Conversion Checklist

Pricing and Economics

Ebook conversion is a one-time production cost. Once the EPUB is built and validated, it can be distributed indefinitely with no per-unit manufacturing cost — no paper, no printing, no binding, no shipping. The economics are fundamentally different from print.

Conversion Cost Factors

Content complexity. A 200-page text-only novel converts at a fraction of the cost of a 200-page cookbook with 80 images and 40 tables. Complexity determines hours, and hours determine cost.
Source file quality. A cleanly formatted Word document or InDesign package converts faster than a PDF that requires text extraction, or a Word file with inconsistent styles and manual formatting.
Fixed-layout requirements. Fixed-layout ebooks require page-by-page construction and are significantly more expensive to produce than reflowable files.
Number of output formats. An EPUB plus a Kindle-optimized file is standard. Adding retailer-specific files or accessibility-enhanced versions adds to the scope.

Retailer Royalty Structures

Each retailer sets its own royalty rates and pricing rules. At a high level:

Amazon KDP — 35% or 70% list price (the 70% option is available for books priced $2.99–$9.99 and includes a per-MB delivery fee)
Apple Books — 70% list price
Kobo — 70% list price (for books priced above a minimum threshold; 45% below)
B&N Press — 65% for books priced $2.99–$9.99; 40% below $2.99
Google Play — 52% list price (default; negotiable for publishers)

These rates change, and each platform has territory-specific rules. Verify current terms on each platform’s publisher dashboard before setting prices.

Print + Ebook Strategy

Most publishers and self-published authors release print and ebook editions simultaneously. The ebook typically prices lower than the print edition — $4.99 to $14.99 is the common range for trade titles, with most fiction ebooks priced at $4.99 to $9.99 and nonfiction at $7.99 to $14.99.

The two formats generally reach different buyers. Print buyers prefer physical books, bookstores, and libraries. Ebook buyers prefer instant delivery, portability, and lower price points. Cannibalization between formats is lower than most authors expect — the more common outcome is incremental reach.

Accessibility in Ebooks

EPUB 3 supports robust accessibility features, and accessible ebooks are increasingly a legal and ethical expectation — not a nice-to-have. An accessible ebook benefits readers who use screen readers, readers with low vision who rely on font scaling, and readers with cognitive or motor disabilities who depend on well-structured navigation.

Core accessibility practices:

Semantic HTML — use proper heading hierarchy (h1 for chapter titles, h2 for sections, etc.), ordered and unordered lists, blockquotes, and other semantic elements rather than visual-only formatting
Alt text for images — every image should have a meaningful alt-text description
Reading order — the content order in the markup should match the logical reading order
Language declaration — the primary language and any language changes within the text should be declared in the markup
Navigation — a complete, functional table of contents and page-list navigation (if applicable)

An EPUB that follows these practices passes accessibility validation tools (such as Ace by DAISY) and is usable by the widest possible audience.

ISBN guide — format-specific ISBN requirements and registration
Book distribution guide — print and ebook distribution channels, aggregators, and fulfillment
Marketing your book — launch strategy, metadata optimization, and platform-specific visibility
Color management guide — relevant for converting print CMYK images to ebook RGB
Book cover design guide — preparing a separate ebook cover from the print cover file

Next Steps

Ready to convert? Send us your source file — print-ready PDF, InDesign package, or formatted Word document — and we will assess conversion complexity and quote the project.
Not sure if reflowable or fixed-layout? Describe your book’s content — we will recommend the right approach based on your interior layout.
Need print and ebook together? If we are printing your book, we can produce the ebook conversion from the same source files as a bundled project, which streamlines the process and ensures consistency between editions.
Have an EPUB that is not passing validation? Send it to us — we can audit, fix, and revalidate an existing EPUB that is failing epubcheck or being rejected by a retailer.