In high school and even college most students are told to aim for around 5-6 sentences per paragraph. I am now trying to write fiction, fantasy specifically, but am hitting a wall when it comes to paragraph length. Most of my paragraphs are around 2-3 sentences, sometimes more, sometimes less. I feel like I'm violating some rule but I know I've seen books use very few sentences per paragraph.
Are there any guidelines to follow or ways to tell if your paragraphs are too short/long?
There are many different thoughts on this. If you are writing a novel, then you can do basically whatever you want (and I'll get to that later), but if it's an academic paper, you should be more rigid with your length.
For academic papers, your assumption was right-- 5-6 sentences is a good length for that paper. You won't want standalone sentences that you sometimes see in novels, that's just not very on-genre. That part is pretty basic.
A novel, however, is something different entirely.
You are able to do many standalone sentences (like I just did above, look at that!), and you have the option of having much longer or shorter paragraphs. The Hobbit, for example, has many long paragraphs. But that was written a while ago, and long paragraphs tend to draw the reader out of the book. Long paragraphs look boring and dull, making the reader step away from the book for long periods of time. So you probably don't want those large paragraphs (more than ~12 sentences). That being said, when you are catching your reader up on some history that is new for the reader and the main character, then long paragraphs can be fine in small portions.
An average length for a paragraph in a novel is anywhere from 1-8(ish) sentences, so that should be an average guide for you. Your style could be that of long rambling sentences,s which is fine, but if that is you, try to cut back on them a bit.
But!
Don't forget to change paragraphs when the voice changes, time changes, something new is introduced, a setting changes, the "camera" moves, or something new is happening. This link is one that explains this topic in more detail.
I hope that helped and happy writing!
Purdue OWL gives a great definition of the concept of a "paragraph":
Paragraphs are units of thought with one adequately developed idea.
In other words, paragraphs are not just clusters of sentences, but instead ideas. The length of the paragraph, therefore, represents how much you develop the idea in the paragraph, and the division of paragraphs should be dictated not by some arbitrary word limit (100-200 words is what I learned in high school), but instead by the clear, logical division of ideas.
If you are having a problem where your paragraphs are too short, you may not be adequately developing the ideas in each of those paragraphs. If they are too long, on the other hand, it's a sign that you're overdeveloping your ideas to the point of monotony, and might be getting too abstract and verbose.
From that definition, we can provide some helpful rules of thumb.
My personal rule of thumb is that if a paragraph reaches 100 words, I should think about either trimming it down or breaking it into two, lest I end up with a wall of text. That's just a guideline, though, not something I rigidly obey. Aside from that, I don't think there are any hard-and-fast rules about paragraph length. A paragraph should be as long or as short as it needs to be, whether that's two sentences or six.
The best example I can think of is the opening paragraph of the climactic chapter of Harry Potter and the Philosopher's Stone. It's only one sentence and three words long, but it says everything that needs to be said:
It was Quirrell.
If that opening paragraph had been a five-sentence description of Quirrell standing in front of the Mirror of Erised, I don't think it would have had half the impact. Very short paragraphs are perfect for those sorts of "wham" moments, as long as you're not over-using them.
Paragraphs should be as long as they want to be. That sounds useless, but it is really the best answer to your question.
The truth of the matter is, in prose writing, there are no hard and fast concrete rules you can apply. Everything is a matter of taste. That doesn't mean that it's the wild west and anything goes - there's writing that is awkward and stilted and unpleasant and that hits the wrong tone, and you want to avoid that. But you need to get used to looking at prose writing from a subjective point of view. Instead of measuring whether you hit the right concrete metrics, you need to think about what you want to achieve and whether the approach you're taking realizes your goals.
In the case of deciding how long paragraphs should be, you're looking at the ideas of sentence structure, pacing, and musicality. In prose writing, you want the way you arrange your words to read pleasantly off the page. For a fight scene, you might want a frantic pace. So short, choppy sentences arranged in short, 1-3 sentence paragraphs give your writing a breathless feel that propels the reader down the page. But when your characters have a chance to catch their breath and emotionally process everything that's happened to them, you probably want a more introspective pace. Long, flowing sentences arranged in dense paragraphs, full of questions asked to nobody and ideas that struggle to find something to connect with, make sense.
Every novel I've read has some paragraphs that are only a few words long, paragraphs that fill up most of a page, and everything in-between.
Don't feel like you have to make each paragraph fit within some kind of measuring stick in order to be Correct. Instead, think about what you're trying to say at each point in your story. Let your paragraphs tell you how long they need to be. Make them musical, and allow them to break up ideas naturally instead of forcibly separating or conjoining ideas that shouldn't be pulled apart or crammed together.
I believe that the answer to this question, in the current fiction writing, is mostly a matter of style or flow of the narrative.
For instance, José Saramago, the Nobel Prize winner of 1998, used to write each of his books as a single paragraph.
