I’ve heard this question floating around again recently. It’s good to see most people know the answer now, but a mix of “long enough”, “depends on the scene you’re writing” and “depends on your style” is not really all-encompassing or detailed enough to really identify the deciding factor. That’s what I’m here for.
So what does sentence length achieve? In a word: pace. There are only two tools a writer has to manipulate pace, and they are sentence structure (of which length is a major part) and diction. I’ve done a post on both pace and diction before in my 5 Tips to Improve Your Fiction Writing.
Advocates of long, elaborate sentences are often misguided by the misconception that good writing requires sophisticated language, which in turn requires length and adjectives. These people often make an appeal to authority fallacy and bring up Hemmingway or Tolkien (I mention these two because I hear them brought up the most often). I want to point out two problems with using these authors as examples. First, language has evolved over time. We no longer use Elizabethan English, for example, so it would be inappropriate to write a story with such language. In general, older books will feature much more elaborate sentence structures. This is just a reflection of the language paradigm of their time. Second, Hemmingway and Tolkien actually do use short sentences to create impact and pace. They may not use it as often but if you go flick through one of their books and specifically look for them, you’ll find the sentences I’m talking about.
Thus, we are now at a position where we must agree that sentence length is used to control pace. There is no argument in this. How you use it and how often you use it is entirely up to your own style, but the bottom line is that your decision should be based on what sort of pace you’re trying to achieve in a particular scene.
So, I mentioned that comments like “long enough” weren’t specific enough (though true). What answer would I give? Everything I’ve said so far, but the crux of the argument is that short sentences create more impact and give an impression of action and pace. Further, you can enhance the sense of action and adrenaline by putting more emphasis on action words (verbs – things the characters are actually doing). On the other side of the spectrum, an emotional scene is less likely to have short, action sentences than a fight scene. It would focus less on action words and more on inner thoughts, and emotional tells. Introspective and emotional sentences would be more appropriate than short, sharp sentences. Just an afterword, remember to use all techniques with an even hand. Don’t go lathering on the short sentences. Or. You’ll. Be. Narrating. Like. This.
In short, the length of your sentences should be dependent on the scene you are writing. I’ve identified the two ends of the spectrum: short sentences for fight/action scenes and long sentences for emotional/slow scenes. I’ve also identified certain types of words you should (or should not) focus on, such as action words and introspective words (words relating to inner thoughts and emotions). Now it’s up to you guys to fill in the blanks and add your own flavour to it.
P.S. I debated adding examples to this post to show you but I didn’t feel like it in the end. There’s an example in my 5 Tips to Improve Your Fiction Writing. Otherwise, just read any good book and you should be able to identify what I’m saying.