Chapter word counts and their running time
Times assume a narration pace of 155 words per minute, close to a typical retail audiobook. Slower, more dramatic readings run up to ten percent longer.
| Words in the chapter | Running time | Where you see it |
|---|---|---|
| 1,500 | About 10 min | Short thriller chapters, early chapter books |
| 2,500 | About 16 min | Fast commercial fiction, many web serials |
| 3,500 | About 23 min | Romance, cozy mystery, most genre novels |
| 5,000 | About 32 min | Literary fiction, fantasy, memoir |
| 7,500 | About 48 min | Epic fantasy, history and other long nonfiction |
| 10,000 | About 1 h 5 min | Long enough that listeners lose their place |
| 18,600 | About 2 h | Right at the usual per file cap |
To time a single passage, use the words to minutes calculator. To read every chapter’s word count straight from an EPUB, use the EPUB chapter extractor.
How listeners use audiobook chapters day to day
Chapters are stopping points. People listen in sessions: a commute, a workout, washing up, ten minutes before sleep. A chapter of 20 to 30 minutes fits most of those, so the listener finishes a chapter and stops at a natural break instead of mid scene.
Sleep timers follow chapters. Most audiobook apps offer an “end of chapter” sleep timer. With a 25 minute chapter it works as intended; with a 90 minute chapter the listener either falls asleep and loses an hour, or picks a fixed timer and wakes up in the middle of a conversation.
The chapter list is the map. Listeners skip back a chapter when they zone out, or jump forward to a part they want to replay. A list of clearly named, evenly sized chapters makes that easy. A list where chapter 7 runs three minutes and chapter 8 runs two hours does not.
None of this means you should rewrite your book. Chapter length in print already follows the rhythm of the story, and listeners accept the same rhythm in audio. The adjustments below are for the outliers.
Audiobook chapter length limits in store specs
Stores that ask for one file per chapter set a maximum per file. At the time of writing, ACX accepts files of up to 120 minutes and asks for opening and closing credits as separate short files, plus a retail sample of one to five minutes. Distributors and other stores publish similar specs, often with a comparable limit. Because these rules change, check the store’s current audio requirements before you export.
At a narration pace of 155 words per minute, two hours is about 18,600 words. Very few novel chapters get there, but nonfiction chapters, omnibus editions and books with no internal chapter breaks sometimes do. Those need splitting before upload.
An M4B file works differently: the whole book is one file with chapter markers inside, so there is no per file limit to hit. Long chapters still feel long to the listener, though, so the same advice applies. M4B vs MP3 explains which stores take which format.
Splitting a chapter that runs too long
Split at the source, before you generate, so the chapter list and the audio files agree.
- 1
Find a scene break near the middle
Look for a change of place, time or point of view close to the halfway mark. Never split in the middle of a conversation.
- 2
Name the parts clearly
Use “Chapter 12, Part 1” and “Chapter 12, Part 2” so the numbering still matches the ebook and listeners can find their place in either.
- 3
Add a heading the importer can see
In a Word file, add a Heading 1 or Heading 2 at the break. In a TXT or Markdown file, add a line such as “Chapter 12, Part 2” or a Markdown heading. In an EPUB, add the new section to the table of contents in your EPUB editor.
- 4
Check the new times
Paste the new word counts into the calculator above and confirm both halves land under an hour, or under your target.
Prologues, interludes and other very short chapters
A prologue of four minutes or an interlude of two is fine as its own chapter. Keeping the same structure as the ebook helps readers who switch between formats, and a short chapter costs nothing extra to produce.
Merge only the fragments that would confuse the chapter list: a one line epigraph, a map caption or a part title page with no text under it. Fold those into the chapter that follows. Front matter such as the cover, copyright page, contents and dedication is set aside automatically when you import, so it never becomes a chapter of its own. The audiobook script format guide covers what else to remove before narration.
Most audiobooks begin with a short opening credit naming the title and author and end with a closing credit. Keep them to a few seconds each.
How many audiobook chapters a typical book has
Rough chapter counts for common book lengths, assuming the chapter sizes most common in each genre.
| Book | Words | Finished length | Typical chapters |
|---|---|---|---|
| Novella | 20,000 to 40,000 | 2 to 4.5 h | 8 to 20 |
| Genre novel | 70,000 to 90,000 | 7.5 to 10 h | 20 to 40 |
| Epic fantasy | 120,000 to 200,000 | 13 to 21.5 h | 40 to 80 |
| Nonfiction | 50,000 to 80,000 | 5.5 to 8.5 h | 10 to 20, often longer each |
Nonfiction chapters are often long. If yours run past an hour, split them at section headings, as described above.
Chapter files and chapter markers come from the same headings
When you export from the AI audiobook generator, each chapter becomes one MP3 in a ZIP with a chapters index, or one named chapter marker inside an M4B. Getting chapter boundaries right before generation means both formats come out right. If you already have separate MP3 chapters from another source, the MP3 to M4B converter joins them into one file with markers.
