How Long Should Your eBooks Be? [Writing]

There was a time before e-publishing when the length of a book was all about page count. It was generally accepted that 240 pages was the minimum length of a novel. If your novel wasn't 240 pages, authors and even publishers would enlarge the fonts and spacing to make the text bigger so the book would achieve 240 pages. With the arrival of e-readers, these rules went out the window. e-readers like Kindles allow the reader to adjust font size and spacing so pages don't matter. It's now all about word count.

I've seen other authors charge ridiculous amounts for very little work; $2.99 for 10,000 words or $4.99 for 12,000 words are some true examples. When I started writing new works for e-readers, I asked myself how long my books should be. How short was too short? How many words would be a short story and how many words would be a good size for a novel? Really, as a self-published author you can do whatever you want, but I felt I needed guidelines to provide a standardized experience for the reader. I didn't want to publish a short story and have my readers feel it was too short to sell on its own, and I didn't want to promote a novel that readers felt was too short to call a novel. To answer the question, I turned to the industry itself.

Let's start with short stories. Amazon sets the standard for e-publishing, in my opinion, and they have a program called Kindle Singles. Amazon describes these books as "writing that doesn't easily fall into the conventional space limitations of magazines or print books." Sounds like short stories and novellas to me. Amazon says, "Kindle Singles are typically between 5,000 and 30,000 words." That means my short stories should be at least 5,000 words long, and novellas around 30,000 words.

As for novels, I found a good guideline in BookBub's guidelines. Their listing guidelines read, "BookBub promotes full-length works, so we do not typically accept listings for books under 150 pages (" or roughly 50,000 words)." That tells me that a novel should be at least 50,000 words.

Now I should mention these are by no means a standard. The Science Fiction and Fantasy Writers of America specifies word lengths for each category of its Nebula award categories as:
Novel - over 40,000 words
Novella - 17,500 to 40,000 words
Novelette - 7,500 to 17,500 words
Short story - under 7,500 words

What do you think? Are these good guidelines for book length? Do you use different guidelines? Would you buy an ebook that was shorter than 5,000 words or a novel for less than 50,000 words? Let me know in the comments.