One of the common questions I get as an agent relates to how long a book should be. Many aspiring authors think about a target number of pages and chapters when they need to focus on word count.

Using pages as a metric for book length likely comes from those who self-publish and are accustomed to being charged per page for their book.

Depending on the type of project, there is an optimum word count that affects the length of a project. There are some variations; but generally, they all fall into a range that gives authors an idea of how to proceed.

There are some dramatic exceptions to whatever general guidelines exist.

A generation ago, chapter books for grade schoolers were generally about 20,000 words and put into formats with larger print and paperback covers. Then along came Harry Potter, and the assumptions about what a ten-year-old would read went out the window. Harry Potter books started at 76,000 words for the first in the series, and another was over a quarter million words.

I have seen proposed projects that are significantly too long, like the 800,000-word memoir that could only be published as a set of books costing $300 to replace where you used to store a Funk & Wagnalls encyclopedia set on the bookshelf. Maybe there could be a payment plan to get a new volume monthly for twelve months?

I’ve also seen “books” that are too short, like the insightful 1,200-word info-piece that should be a free download PDF or a booklet given out on the street corner.

Neither of these examples is commercially viable. The first is too expensive to publish, and the second would not command a selling price that would make it worthwhile. In other words, they cannot be published and make financial sense for a publisher.

There are 800,000-word projects, like biblical commentaries, a history of human civilization, or the Bible (yes, it is around 800,000 words). But they are not the story of your family.

The specifics of commercial-length projects vary from category to category and by publisher.  So, what is commercial length?  It’s the word count that allows a publisher to create it for a reasonable and optimal price so it can sell the most copies and meet their financial targets.

These are broad generalities, of course, but here’s a start on word counts for your consideration:

Children’s board books – about 100 words

Early readers (ages 5-7) – 1,000-3,500 words

Chapter books – 15,000-35,000 words

Middle grade – 30,000-45,000 words

YA fiction – 50,000-80,000 words

Adult fiction novellas – 35,000-45,000 words

Other adult fiction – 70,000-100,000 words

Sci-fi/fantasy – 80,000-100,000 words

40-day devotionals – 30,000-40,000 words

90-day devotionals – 45,000-60,000 words

365-day devotionals – 90,000-100,000 words

Bible studies – 10,000-20,000 words

Memoirs – 40,000-70,000 words

Academic/reflective – 50,000-100,000 words

Other adult nonfiction – 40,000-70,000 words

These are general guidelines, not chiseled-in-stone laws. It’s always OK to do what you think is best, but the publisher may ask you to cut or expand.

Just stay away from books written either at blog or biblical length!