How to Convert EPUB to M4B Audiobook on Mac (Offline, with Chapters)

An EPUB is designed for reading, but sometimes you want to listen to the same book: on a walk, during a commute, or while doing something else. A chapter-marked M4B audiobook lets you keep the narration in one file instead of juggling dozens of audio clips.

You can convert a DRM-free EPUB to M4B on Mac using Spokio, an offline text-to-speech app. Spokio imports the ebook into a chapter-based project, generates English narration locally, and exports a single M4B file containing the project title and named chapter markers.

This guide walks through the actual Mac workflow, including how to keep chapter order intact, what to check before export, and how to listen in Apple Books.

Quick answer: EPUB to M4B on Mac

1. Open Spokio for Mac and choose Create Audio → EPUB Project.
2. Select a DRM-free EPUB, choose a project name, voice, and speed, then click Create Project.
3. Open the project and review the imported Chapters.
4. Use the project generation action and choose Generate Unfinished Items to create the narration.
5. Click Export Audio…, select the generated chapters, turn on One combined audio file, and choose M4B Audiobook.
6. Export to a folder, then import the M4B into Apple Books or another audiobook player.

What you get: one playable M4B file with chapters in project order. You can optionally export separate MP3 chapter files at the same time.

Important: this workflow is for Spokio on Mac, not the lighter Spokio iPhone app. It requires a readable EPUB without DRM; it does not remove copy protection.

What is an M4B audiobook, and why use it instead of MP3?

M4B is a format commonly used for audiobooks. The practical difference is not just the file extension: an M4B can hold an entire book and chapter markers within the same audio file.

If your goal is to listen to a novel or nonfiction book from beginning to end, M4B is usually the cleaner choice. If you plan to edit every chapter separately, keep the MP3 outputs too.

Spokio’s combined M4B export writes the project title and named chapters in the project’s order. Do not confuse that with merely renaming an M4A or MP3 file to have an .m4b extension; chapter information has to be written into the file.

Before you start: use a readable, DRM-free EPUB

You will need:

• A Mac running macOS 15.6 or later (Apple Silicon and supported Intel Macs can run Spokio).
• Spokio for Mac with access to Pro project generation and export features.
• An English-language EPUB that you are allowed to process and that does not have DRM.
• Enough free storage and time for generating a full book. Longer books take more processing than a short voiceover.

Good test inputs include your own manuscript, a freely distributed DRM-free book, or a public-domain EPUB from a reputable source. For an initial trial, start with a short book or a few chapters so you can check pronunciation and pacing before generating hours of narration.

What about Kindle or Apple Books purchases? Buying an ebook does not necessarily give you an unprotected EPUB you can feed into another app. Many store books use DRM or stay within the seller’s app. Spokio is not a DRM-removal tool; use a legitimately accessible file and respect the rights and terms attached to the work.

Step 1: Create an EPUB Project

1. Launch Spokio on your Mac.
2. Click Create Audio and choose EPUB Project from its menu.
3. In the New EPUB Project sheet, click the control to choose your EPUB file.
4. Give the project a recognizable name, such as The Short Stories Collection.
5. Choose a default Voice and Speed, then select where the project should be stored.
6. Click Create Project. Let the import and validation finish, then choose Open Project.

Spokio parses the EPUB into a chapter-based project rather than treating the whole book as an undifferentiated wall of text. The source is copied into the project package during import, so the project has its own copy of the book it was created from.

The chapter count depends on how the EPUB was authored. A well-structured book with clear sections is easier to work with than one that merges the entire text into a single section.

Step 2: Review the extracted chapters before generating

In the project sidebar, find Chapters. Select a few entries and read the text that Spokio extracted.

Check these four things:

• Chapter boundaries: Does each chapter start and end in the expected place?
• Chapter titles: Are the names sensible and in the correct order?
• Unwanted text: Are there navigation labels, footnotes, or front matter you would rather not hear?
• Pronunciation: Are there abbreviations, symbols, names, or unusual spellings worth testing?

This review is worth doing. The M4B export uses the project’s selected chapter order and titles. If the source EPUB has poor structure, exporting it perfectly will not fix the content itself.

For a book with distracting front matter or inconsistent chapter boundaries, correct the source or editable chapter text before committing to a full synthesis job. Do not assume every EPUB will import cleanly.

Step 3: Choose a voice and generate the audiobook narration

Spokio supports built-in English voices and custom voices created from audio you have permission to use. The default voice and speed can be chosen when creating the project, with per-item settings available for more control.

For long-form listening, choose a voice that stays comfortable for 20 or 30 minutes, not just one that sounds impressive during a 10-second preview. Test a sample that includes dialogue, long sentences, and names.

Then generate the chapters:

1. Use the project’s Generate action.
2. For an ungenerated project, choose Generate Unfinished Items.
3. Let Spokio work through the queued chapter jobs.
4. Listen to representative sections when generation finishes.

You do not need to upload the EPUB or its text to a speech API. Speech generation runs locally on your Mac, although downloading the app and receiving updates uses an internet connection.

If you revise a chapter after generation, use Regenerate Outdated Items so its audio matches the latest text and settings. Avoid starting the M4B export while some intended chapters still show missing or outdated audio.

Need a deeper explanation of why book-length narration takes care? See TTS for Audiobooks: Can AI Narration Handle Long-Form Content?.

Step 4: Export one M4B file with named chapters

Once your chapters have generated audio:

1. Open the EPUB project and click Export Audio… in the project header.
2. Review the chapter table. Each row shows a title, duration, and readiness status.
3. Use Select All to include the ready chapters, or choose the exact chapters you want.
4. Under Output, enable One combined audio file.
5. In Combined format, select M4B Audiobook.
6. If you only need the audiobook, turn Separate files off. Leave it on with MP3 selected if you also want editable, individual chapter audio.
7. Click Export and choose a destination folder.

The current export sheet starts with M4B as the combined format and MP3 for separate files. You can keep both outputs or disable the one you do not need.

Spokio combines selected chapter audio in project order, embeds named chapter markers and the project title in the M4B, and saves the output in a newly created folder. When separate files are enabled, they are written into a Chapters subfolder.

For example, a project named My Book could export:

My Book/
  My Book.m4b
  Chapters/
    01 - Introduction.mp3
    02 - Chapter One.mp3
    03 - Chapter Two.mp3

The exact names depend on your project and its chapter titles.

Do not ignore missing chapters. If some chapter audio is unavailable or outdated, the export sheet shows that status. A combined export with omitted chapters will not magically fill the gaps. Generate or repair those chapters first, unless you intentionally want a partial audiobook.

Step 5: Import the M4B into Apple Books

To listen using Apple’s Books app on your Mac:

1. Open Books.
2. Choose File → Import.
3. Select the exported .m4b file and import it.
4. Open the audiobook and check playback, total duration, and chapter navigation.

Apple documents this import workflow in its Books User Guide for Mac.

Different players display chapter names and book metadata differently. Always test a real export in the app you intend to use before converting a large library.

The result is a self-contained audio file. Once generated, you can keep the audiobook for offline playback without repeatedly running text-to-speech.

Common EPUB-to-M4B problems

“My EPUB cannot be imported”

First check whether it is a standard, readable EPUB and not a DRM-protected store download. If it is a readable but unusually formatted file, try a simpler EPUB to separate a source-file issue from a project issue.

“The chapters are wrong or missing”

M4B chapter markers follow the entries in your Spokio project. Check the imported Chapters list before generation and export. Some EPUBs use inconsistent internal navigation or structure, so their detected chapter layout can need cleanup.

“The export skips part of the book”

Open Export Audio… and check the chapter table. Missing, stale, excluded, or unselected chapter audio can produce an incomplete selection. Make sure the intended items are generated and selected.

“The voice sounds uneven across chapters”

Test the voice and speed on multiple passages, and review any chapter-specific settings. Long-form synthesis can expose unnatural pauses or pronunciations that short clips hide. Fix an affected chapter and regenerate it rather than rebuilding every chapter by default.

“Generating a whole book takes too long”

On-device generation uses your Mac’s hardware. Start with a few chapters, use the background queue, and allow time for a longer book. Actual generation time varies by hardware, text length, and settings; there is no reliable universal minutes-per-book estimate.

Frequently asked questions

Can I convert EPUB to M4B without an internet connection?

Yes. After installing Spokio and any necessary local resources, its speech generation happens on-device. You do not need a cloud TTS API key for the normal workflow.

Does the M4B keep the ebook’s chapters?

Spokio’s M4B Audiobook export includes named chapter markers in project order. Verify the extracted chapter structure first; the export reflects the chapters available in the project, not necessarily every section a publisher intended.

Can I export MP3 and M4B at the same time?

Yes. Enable One combined audio file → M4B Audiobook and Separate files → MP3 in the Mac project’s export sheet.

Can I do this with Spokio on iPhone?

The full EPUB Project → chapter generation → combined M4B export workflow described here is for Mac. Spokio for iPhone focuses on lighter, individual audio-generation workflows.

Does it work on Intel Macs?

Spokio for Mac supports both Intel and Apple Silicon hardware running macOS 15.6 or later. Generation speed will vary by machine. See Mac compatibility and requirements.

Is converting any ebook legal?

Only convert material you are permitted to use. Ownership of a digital book does not automatically imply permission to bypass DRM or distribute derivative audio. Rules depend on the rights in the work, your jurisdiction, and the terms of the source.

A simpler way to turn an ebook into an audiobook

If you only need an app to read a few pages aloud, macOS built-in speech may be enough. See How to Listen to eBooks on Mac.

But if you want a reusable audiobook file with chapters, the workflow is different: import EPUB → review chapters → generate audio locally → export M4B → listen.

Try Spokio for Mac to turn your own DRM-free EPUB into a chapter-marked audiobook, without uploading your book to a cloud TTS service.