Here is another question that ends up on wattpad... How long should a chapter be? What about a paragraph? How does that translate to word? To a novel how many words is ok? To a story on Wattpad should it be more or less? To the style of book I want to write? Okay, Okay, that's a lot of questions actually, so let's go ahead a break it down for you.
If you're trying to decide how long you should write a chapter, the go to answer is that it should be exactly as long as you want it to be. I'm not entirely convinced of that answer. First off, that doesn't help you achieve any kind of goal in writing. If you write long, bloated work and could benefit from chopping it down, this advice is useless. If you write short, detail-less chapters, this is also useless.
I find myself facing the argument "well, this person once wrote a chapter only one word long, so that makes it a free game."
My response to that is... no... it doesn't. There are typical averages for writing. It will fluctuate greatly based on your style, but don't let that give you the idea that you can do whatever you want. There needs to be a "reason" you're going outside the averages. There should be a point to it. If you're just doing it because you don't feel like writing any more or because you lack the skill to write more than 500 word chapters, that is not an excuse.
Anyway, now that I've explained some of that... let's break this down with some averages. Please note that these can vary. How many words per page depend on how you write. A dialogue heavy writing with many word breaks, or use of large words versus small words, can change the amount a lot. Also, I'm assuming Calibri or Times New Roman at font size 11 or 12 respectively.
A single word page - Is ~500 words, going up to as much as 800 or as low as 400.
A single novel page runs from 200-400 words, heavily influenced by the size of font, book, etc...
A chapter size can range from 1000-7000 words. A good average is 2000-3000 words. If you are writing young adult that can go smaller, if you writing advance technical stuff that can go bigger.
Some authors write chapters as long as 12k words, and this can be okay for some, and a bit wordy for others. Deciding how long your chapter should be depends a bit on your target audience. Familiarize yourself with the type of genre you want to write, and try to pick the sizes you aim for based on that.
This means in a novel, a chapter can usually run from 6-28 novel pages or 3-14 word pages.
Naturally, a poem or a chapter less children's book would follow different rules.
Paragraphs have no specific sentence or word count. Avoid writing one over six sentences long. They can be as short as one sentence, especially when using dialogue.
Short Story - Under 7,500 words
Novella (Or Young Adult Novel) - 7,500 words to 17,500 words
Novelette - 17,500 words to 60,000 words
Novel - 60,000 words and more
These numbers are subject to change, there is nothing that officially says anything can't be a novel at 59,000 words.
A young adult Goosebump book from RL Stine is right under 20,000 words.
Twilight is 118,000 words, roughly.
Hunger Games was 102,700 words.
The first Harry Potter was 77,000 words and the fattest Harry Potter (book 5) was 250,000 words.
Most Standard Novels are around 80,000-120,000 words.
Larger Novels and Epics (Game of Thrones, etc...) are from 250,000 to 400,000 words.
Most books don't go over 400,000 words.
The Bible (new and old) is 800,000 words. Mind you, there are 66 books in the bible, so each book is only like 10,000 words. (Yes, I know the exact math of 800,000/66. There are many different versions of the bible with different word counts, and some books are very short, while some are very long. I was giving a rough median... which is actually closer to 5000 if we're being exact)
Anyway, hopefully those numbers put your writing into perspective for you. If you are trying to decide how long your chapters should be, look at how long you typically write. If you struggle to get to 1500 words, you might want to set 1500-2000 as a goal to force yourself to write more. If you easily pump out 6000 word behemoth, you might want to limit yourself to 5000 words to try to force your writing to be cut down.
The next thing you need to ask yourself is "What happens in this chapter?" Write down what physically happens during your chapter. If you're at 3000 words and nothing really happened, then your work is bloated. If you're at 6000 words and fifty things happened, maybe you could break that into two chapters.
Always balance how much happens in your chapter with how many words, it takes to say it. Know that the more you write without stuff happening, chances are the more boring your chapter will become to the reader. If that's the case, either cut it down, or write it in a way that keeps your reader invested in the story, even through the parts that drag.
So yeah, develop your own style and stick with it. Avoid massive chapter variation, rarely should you go from a 500 word chapter to a 5000 word chapter and back again. There is no excuse for that. Still, do what works and what flows well. Remember the overall flow of your story and stick with it.
Good Luck and Happy Writing!