Writing nonfiction: the “length” secret
Here’s a simple answer.
Look at it this way. Before ebooks, to get a nonfiction book published, you needed to convince a publishing house to publish it. So, the length was pretty much determined by the publisher. If your book was too long, it cost too much; the publisher couldn’t recoup his investment. If it was too short, it was a booklet, rather than a book.
Those constraints have gone. Ebook retailers like Amazon don’t care how long or short your ebook is. As a rule of thumb, I like the ebooks which I write for myself or ghostwrite to be over 5,000 words. That said, I’ve recently completed a series for a client, and each of the ebooks was around 4,000 words. Each one covered the topic, and that’s the essence of publishing nonfiction today: when you’ve delivered on your promise, your work is done.