EPUB Conversion Services: How Publishers Should Choose a Production Partner

EPUB Conversion Services: How Publishers Should Choose a Production Partner

Converting a book to EPUB can sound simple:

Source file → EPUB → delivery.

For a straightforward novel created from clean source files, the process can sometimes be relatively simple.

For a publisher's catalogue, it rarely is.

Real publishing lists contain:

• Word files;
• InDesign packages;
• XML;
• PDFs;
• scanned books;
• tables;
• footnotes;
• mathematical content;
• illustrations;
• indexes;
• multilingual content; and
• legacy titles created decades ago.

The question publishers should ask is therefore not:

“Can this supplier create an EPUB?”

It is:

“Can this supplier consistently transform our different source types into structured, validated, usable EPUBs at catalogue scale?”

Direct Answer: What Should Publishers Look for in an EPUB Conversion Service?

A strong EPUB conversion partner should demonstrate capability across:

Source assessment → content reconstruction → semantic structure → navigation → images and complex content → accessibility → validation → human QA → reading-system testing → controlled delivery

Before outsourcing hundreds or thousands of titles, give the supplier a representative pilot set containing both simple and difficult books.

Do not evaluate a vendor using only a clean fiction title.

What Are EPUB Conversion Services?

EPUB conversion services transform publishing source content into an EPUB digital publication.

Source formats commonly include:

• Microsoft Word;
• Adobe InDesign;
• XML;
• HTML;
• PDF;
• scanned pages;
• OCR output; and
• legacy publishing files.

Current vendors commonly advertise EPUB conversion from several of these source formats. For example, current competitor pages mention Word, PDF, InDesign, XML and scanned/backlist sources.

But input flexibility is only one part of the evaluation.

The quality of the resulting structure matters more.

EPUB Conversion Is Not Just File Conversion

Consider a PDF.

The page visually communicates:

• Chapter title
• Heading
• Paragraph
• Image
• Caption
• Footnote

But a PDF-to-EPUB conversion workflow needs to determine what those elements mean.

A heading should become a heading.

A list should become a list.

A quotation should be represented appropriately.

A table should remain a table.

An informative image needs an appropriate text alternative when accessibility is part of the requirement.

That distinction is fundamental:

Appearance describes how content looks. Semantics describe what content is.

A professional EPUB workflow preserves meaning rather than merely reproducing appearance.

Reflowable vs Fixed-Layout EPUB

One of the first vendor decisions should be choosing the appropriate format.

W3C's current EPUB specifications continue to treat reflowable content as the normal model while supporting fixed-layout publishing where preserving layout is necessary.

A vendor should not automatically recommend fixed layout simply because the print PDF has an attractive design.

Ask:

Does the spatial layout carry essential meaning?

If not, reflowable EPUB is often the stronger digital format.

Source Quality Determines Conversion Difficulty

Word → EPUB

Often relatively straightforward when Word styles are used consistently.

Problems appear when documents use:

• manual formatting;
• tabs for alignment;
• repeated spaces;
• inconsistent heading styles;
• text boxes.

InDesign → EPUB

Can provide a useful production source, but export alone does not guarantee a production-ready EPUB.

The output still needs review for:

• semantics;
• reading order;
• navigation;
• images;
• CSS;
• accessibility;
• validation.

XML → EPUB

Structured XML can provide an excellent basis for systematic conversion.

The strength depends on the quality and consistency of the source markup.

PDF → EPUB

PDF presents a larger reconstruction challenge.

A PDF primarily represents a finished page.

The workflow may have to reconstruct:

• paragraphs;
• headings;
• columns;
• lists;
• tables;
• captions;
• reading sequence.

Scanned Book → EPUB

The workflow becomes longer:

Scan → image processing → OCR → correction → structure → EPUB → QA

Current backlist service pages similarly describe OCR cleanup and reconstruction before EPUB production for older source material.

Seven Areas to Evaluate in an EPUB Vendor

1. Semantic Structure

Ask how the supplier handles:

• headings;
• lists;
• quotations;
• tables;
• figures;
• captions;
• footnotes;
• landmarks.

Do not judge only by visual appearance.

Open the EPUB structure.

2. Navigation

A professional EPUB needs usable navigation.

EPUB's navigation document provides the publication's global navigation layer and is required by EPUB.

Review:

• table of contents;
• hierarchy;
• chapter links;
• landmarks where appropriate;
• page navigation where required.

3. Accessibility

Accessibility should be discussed at project-definition stage.

Ask whether the workflow covers:

• semantic HTML;
• meaningful heading hierarchy;
• image text alternatives;
• tables;
• reading order;
• language;
• navigation;
• accessibility metadata;
• assistive-technology QA.

Do not accept “accessible EPUB” as an undefined marketing phrase.

Ask:

Accessible against which specification and verified how?

4. Complex Content

Give the supplier examples containing:

• complex tables;
• mathematics;
• diagrams;
• footnotes;
• references;
• multilingual text;
• sidebars;
• image-heavy sections.

This exposes production capability far better than a text-only sample.

5. Validation

EPUB validation should be part of delivery.

But validation answers:

Is the EPUB technically valid?

It does not fully answer:

Is the book usable and accessible?

Current competitor offerings increasingly mention EPUBCheck and accessibility validation as delivery controls, demonstrating that validation has become an expected part of the market.

6. Human QA

Ask what humans inspect after automated checks.

Examples include:

• TOC accuracy;
• reading order;
• image placement;
• alt-text relevance;
• table comprehension;
• footnote navigation;
• visual rendering;
• cross-reference behaviour.

7. Production Scale

Converting five titles is different from converting 5,000.

At catalogue scale, ask about:

• title classification;
• production batches;
• exception handling;
• QA sampling;
• version control;
• delivery reports;
• naming conventions;
• escalation workflows.

What Should Be in an EPUB Conversion Pilot?

Use several representative books.

A diverse pilot reveals whether the vendor has a production system, not simply a conversion tool.

EPUB Conversion Vendor Checklist

Before selecting a partner, verify:

• Source formats supported
  
• Reflowable/fixed-layout decision process
  
• Semantic HTML structure
  
• Navigation document
  
• Table-of-contents QA
  
• Image extraction/optimization
  
• Alt-text workflow
  
• Table handling
  
• Mathematics handling
  
• Footnote/endnote handling
  
• Accessibility metadata
  
• EPUB validation
  
• Human QA
  
• Reading-system testing
  
• Correction/retest workflow
  
• Batch reporting
  
• Version control
  

Automated Conversion vs Production Conversion

Automation is valuable.

But the goal should be:

Automate predictable work and escalate semantic decisions to people.

Red Flags When Choosing an EPUB Supplier

Be cautious if a supplier:

Quotes thousands of titles without examining samples.

Source complexity matters.

Promises accessibility based only on automated conversion.

Semantic and usability issues require judgment.

Cannot explain validation.

A publisher should know what happens before delivery.

Uses the same workflow for every book.

A novel and an illustrated textbook are not equivalent production problems.

Cannot explain correction handling.

Failed files should be corrected and retested.

A Scalable EPUB Production Workflow

Stage 1 — Intake

Inventory:

• title;
• ISBN;
• source type;
• complexity;
• required outputs.

Stage 2 — Classification

Assign production route.

Stage 3 — Source Cleanup

Correct obvious source problems.

Stage 4 — Conversion

Create structured EPUB content.

Stage 5 — Accessibility Work

Apply agreed accessibility requirements.

Stage 6 — Automated Validation

Run EPUB and agreed accessibility checks.

Stage 7 — Human QA

Review semantic and visual quality.

Stage 8 — Reading-System Testing

Test representative outputs.

Stage 9 — Correction

Resolve defects.

Stage 10 — Retest and Delivery

Deliver only after acceptance criteria are met.

The scalable model is:

Classify → Convert → Validate → Human QA → Correct → Retest → Deliver

How Gentize Supports EPUB Production

Gentize supports:

• EPUB2/EPUB3 conversion;
• Accessible EPUB/EPUB3;
• Backlist conversion;
• OCR/post-scan processing;
• XML/structured conversion;
• Alt text, including complex content;
• Screen-reader and keyboard testing;
• Human accessibility QA.

Relevant verified Gentize proof points include:

35,000+ title large-scale academic digitization project, delivering scanning, OCR, EPUB, POD, and accessible PDF.

Gentize also has a 200+ member production team and 50+ A11Y-certified testers with visual impairments.

These capabilities are especially relevant when a project combines:

legacy sources + conversion + accessibility + QA + catalogue scale

Internal verification before publication: If using “1,000 books per day digitization capacity” in this article, confirm that this capacity statement is approved for public website use. I have therefore not relied on it in the core article.

Final Takeaway

Choosing an EPUB supplier should not be based solely on:

price per page or price per title.

Evaluate:

source handling + semantic quality + accessibility + validation + human QA + scalability

A strong pilot should answer one question:

Can this production workflow handle the difficult titles as reliably as the easy ones?