Most writers I know go by word count when they're writing. They have a target in mind that a novel must be in order to be considered a novel.
Of course, most of the writers I know have a background in print, not ebooks. I'll take a guess and say that ebook-only writers do the same. However, I've come to realize that a lot of ebook-only writers don't have a firm grasp about the length of a novel versus a novella versus a short story.
According to the reviews I read, readers certainly have an opinion as to what constitutes a novel, and they're happy to jump on the unwary author whose book length doesn't measure up.
With that thought in mind, here are some guidelines I've put together that might help. Next week I'll revisit this discussion and define some of these forms of writing to provide more clarity and will also break down word length of novels by genre.
Word Lengths: Adult Trade Fiction
Micro-Fiction: about 100 words
Flash Fiction: 100--1,000 words
Short Story: 1,000--7,500 words
Novellette: 7,500--20,000 words
Novella: 20,000--50,000 words
Epic Novel: 110,000+ words
Word Lengths: Juvenile Fiction
Middle Grade: 25,000--40,000
Young Adult (YA): 45,000--80,000 (genre dependent)
Check back next week for more about this subject, definitions of these classifications, and a word count breakdown by genre.
A smart writer must know past publishing standards because those have a bearing on reader expectations.