Does the average scene-word-count lessen for a YA/children's novel and increase for, say, an adult thriller?
On average, chapter length increases with intended reader age, but chapter length variance increases also. That is:
On average, chapters in children's books are shorter than chapters in books for juveniles which are in turn shorter than chapters in books for adults.
There is quite some disagreement about ideal chapter length, but here is one example for one author's opinion:
- 200-500 words for early chapter books
- 500-1500 for middle grade
- 1500-2500 for tween
- 1500-3500 for YA
- 2000-4500 for adult
You will find differing but similar numbers when you search for ideal chapter lengths.
Between different books, chapters in children's books are more similar in length, while the length of chapters between different books for adults may vary more widely.
There are books for adults with one-page chapters, and books for adults without any chapter division. Such extremely short or extremely long chapters are uncommon in children's books.
Within one book, chapter length is more uniform in children's books than in books for adults.
In a book for adults a chapter of 3000 words can be followed by a chapter of one sentence. In a children's book all chapters are usually of the same approximate length. I have counted chapter length in one famous older MG adventure novel and found all chapters to be within two hundred words of each other.
What is the ideal chapter length?
When you write for children (under 15), you must remember that
they read more slowly than adults
reading is more strenuous for them
they are not able to wait as long for a reward (e.g. resolution of chapter arc at chapter end)
This means that a chapter should be no longer than about 5 to 10 minutes of reading for elementary school children, and no longer than about 15 to 20 minutes for MG readers (these numbers are from my experience with my own children, but are of course open for debate, as always).
The easiest approach to finding ideal chapter length in my opinion is taking bestselling books for your intended age range and counting the words in their chapters. This is easy to do, when you buy or lend an ebook and paste the chapters into a word processing software.
Do not forget that word count varies between languages, so do this research for the language you write in!