how many words is a children's book
Rating Newest Oldest. Best Answer: It looks like 40,000 words is the average acceptable length for books for kids in the 9-12 range. Obviously, you could write a book with more words but I think that kids books need to be more careful about the length than adult books. If you were talking about adult books I would say that the story is over when the story is over, and that length should not dictate the story in any way.