One of the questions that new writers always ask is "How long should my non-fiction book be?" In this article I'm going to attempt to answer that question.
However, part of the reason that new writers find it difficult to pin down an answer is because the answer is so difficult. It is not as straight forward as it seems.
First off, you need to make two decisions. Specifically, you need to decide what type of book you will be writing and how you will be publishing that book. For example, are you going to write an eBook and give it away as a bonus? Or are you going to sell it on Amazon? Are you going to write a popular how-to and use a traditional publisher? Or are you going to write a textbook and sell it through university bookstores?
The form of the book often dictates the size of the book. While the topic will have a great deal of influence, there are many other elements you need to take into account. Many of these are marketing related.
First off, you need to establish a standard length of a page. Some writers will claim there is only one standard length of a page. Unfortunately, they never agree on what the standard is! Typically, fiction uses 250 words per page, although 300 is also a common value. Non-fiction typically has longer sentences and less white space because it does not have dialogue. 300 to 500 words are sometimes used as the yardstick, although 250 is also used. Personally, I, somewhat arbitrarily, use 250. But like all the numbers when discussing book length, you should consider them as yardsticks rather than firm numbers.
Now that we have the length of a page – even an arbitrary one – we can go on to estimate the size of books and articles.
Take a look in your business library. You will find that almost all your books are more than 100 pages long (about 25,000 – 50,000 words depending on your style). By fiction standards that is considered very short – novella size in fact. In fiction, a short book is between 50,000 to 80,000 words (roughly 200 – 300 pages in paperback). Although Science Fiction and some other genres have been creeping up and can now exceed 400 pages (200,000 words). A typical "popular" business book runs 25,000 to 75,000 words. Over that size is the territory of the academic or technical business book.
Typically you will find that books groups naturally after about 100 pages. The reason for this is related to the pricing of a print run. The cost to produce each book is related to the format size (eg trade paperback, paperback, letter etc.), the binding, and the number of pages. This latter tends to be priced at the 100 page mark so preferred lengths tend to come in multiples of 100. For example most short fiction runs at 200 pages (about 50,000 words (romance, westerns etc.). The next step is long fiction at 300 pages (about 75,000 words). Extra long is usually around 400 pages (100,000 words) although it can go beyond.
Ultimately, you need to check the local bookstore to determine the appropriate size. You'll find that certain markets have a preferred size (or sizes). Some publishers will also list their preferences in directories like Writers' Market, although most now prefer to make the writer guess.
Of course, what you wish the length to be, and what the actual length will be can be quite different.