What do you do when you're writing a book that you want to be a full-sized novel when you're done, but while you're writing it you realize that you're not going to make it to that many words?

This is a common question that comes up at writers’ conferences—it seems that it’s not that unusual of a problem. The main thing to remember is to not add words for the sake of adding words.

Readers are much more interested in an engaging and well-told story than they are with word count. And now with the emergence of e-readers, length is becoming less and less of a concern for publishers. 

Genre affects reader expectations about length. Generally, literary novels, romance and young adult fiction can get away with being shorter. Complex historicals, thrillers, fantasy, and science fiction are typically longer.

As a rule of thumb, I’d suggest that if your story is fewer than 30,000 words you call it a short story. If it’s between 30,000 and 60,000 call it a novella. From there on up, most people will consider it a novel. Most novels don’t exceed 130,000 (although several of mine have); beyond that the story might realistically be broken into two 375 pages books.

I’ve never had to work through having to add words myself (usually I’m trying to reduce my word count), but here are my thoughts about it if you feel the need to add to your story.

(1) Be concise. Make every word count. If you can make your story shorter, do it. If you can make it longer but you don’t need to, don’t do it.

(2) If someone asks you to “flesh out” your story, take a careful look at it to make sure you’ve rendered every scene in a way that readers can see what’s happening, that you have created a protagonist who is sufficiently three-dimensional, and that the story is emotionally engaging enough to keep up reader interest. If it seems to you that “fleshing out the story” just means “increasing the word count to a predetermined number,” then push back against making the changes.

(3) Don’t add a subplot just to create a longer story. Only add a subplot if it provides necessary dimensionality to the protagonist. Every “subplot” is really another facet of the main plot and if you can drop or add a subplot without altering that, then drop it.