Calibre EPUB to Audiobook: From Your Library to a Full-Cast M4B

What calibre text to speech can do today

calibre's E-book viewer has a Read aloud button. Since the 8.0 release it uses the Piper neural text-to-speech engine, which runs locally, so no text is sent to a cloud service, and it can also use your operating system's voices. The word or sentence being read is highlighted as you go, which makes it good for reading along at your desk.

calibre's book editor goes a step further for authors: a tool in its Tools menu uses Piper to add audio overlays to an EPUB, so the book can be read aloud even in reading software without text-to-speech, and simple markup can give different parts of the book different voices. Both are listening features built around the ebook. calibre's manual doesn't describe exporting an MP3 or M4B audiobook you can take to any player, and voices per character are assigned by hand.

TTS to MP3 and other calibre audiobook plugins

If you're looking for a calibre audiobook generator, the closest thing is a plugin. The best-known EPUB to MP3 calibre plugin is TTS to MP3 by jackie_w on the MobileRead forums. It records a set of MP3 files, usually one per chapter, for a non-DRM EPUB, AZW3 or KEPUB in your library, using Windows SAPI5 voices. Its thread now carries two notes from the author: ongoing support has stopped, and since September 2024 the plugin doesn't work in calibre 7.18 or later.

Other projects use calibre only as a converter, pulling the text out of an ebook and passing it to an open-source or online TTS engine outside calibre. They can work well if you're comfortable with the command line, and they read in one voice unless you split the text yourself.

Exporting a DRM-free EPUB from calibre

If the book is already an EPUB, select it, open Save to disk and choose Save single format to disk, then pick EPUB. If it's a DRM-free MOBI, AZW3, DOCX or another format, run Convert books with EPUB as the output format first; calibre converts between most ebook formats, DOCX included, and a DOCX upload works here too.

A minute of tidying in calibre pays off. If the contents list is wrong, fix it with calibre's Table of Contents editor (Tools → Table of Contents → Edit Table of Contents in the book editor), because chapter titles come from there. If a chapter is split oddly, or one file holds several chapters, split or merge files in calibre's book editor before you save the copy.

Chapters from the EPUB table of contents

In a calibre EPUB to audiobook conversion, each file the table of contents points to starts a chapter and takes its title from the contents entry. Files with no entry join the chapter before them, and the cover, title page, copyright page and other front matter are suggested to leave out. Those chapters become the markers in the M4B and the file names in the ZIP, so a clean contents list in calibre turns directly into clean navigation in the audiobook.

A full cast vs one system voice

System voices read every line the same way. In a full-cast export, a passage like "Leave it," Hester said. "It's mine to carry." Tom didn't move. becomes Hester's voice for her two lines and the narrator for the rest. You can add a note such as [quiet, firm] before her line, regenerate any single line that lands wrong, and keep the same cast for every book in a series. For a close look at casting, see multi-voice audiobook; for the whole workflow, the AI audiobook generator.

Back into your library: adding the M4B

calibre keeps one file per format in each book record, so a single M4B, or one MP3 for the whole book, fits better than a ZIP of chapter files. Select the book, right-click Add books and choose Add files to selected book records, then pick the M4B. The audiobook now sits next to the EPUB it came from, which closes the loop on calibre EPUB to audiobook.

The M4B carries the title and author as tags, but not calibre's cover, series or other metadata, so add a cover in your audiobook player or tag editor if you want one.

DRM: what calibre won't open, and shouldn't

calibre's own FAQ says most purchased EPUB books have DRM, which prevents calibre from opening them. FullCastBook is the same: it opens DRM-free files only, and it doesn't remove DRM or point you to anything that does. Books you can use are the ones you wrote, public-domain editions, and DRM-free purchases. Kindle books follow the same rule; see Kindle to audiobook. Free credits on sign-up cover a short sample chapter, and the playground on the home page lets you hear the voices first; full books need a plan, see pricing.