Chapter length varies by context
C.J. Bennett
I used to write chapters that were within 1.5-3K words. Why? I read somewhere that this is the ideal length. Turns out this advice is garbage. Here's what you actually need to know about chapter length.
The ideal length
Doesn't exist! Think about the context within which the decision sits instead.
By genre
Readers have certain expectations for genre conventions. A 250-page romance novel is going to turn readers away with a 12K word chapter. But in an epic fantasy novel? Knock yourself out. The point is to be aware of reader and genre expectations.
By limitation
Sometimes you need to write to a wordcount (such as being published with your debut crime fiction novel, you'll struggle to get any representation over 120K words. Might even be lower). If you have a wordcount restriction like this, you might need to be aware of how long your chapters are, simply to get over the line on count. That still leaves you with room to decide on whether you do more, but shorter, chapters, or fewer, but longer chapters.
By narrative depth
In my specific case, I'd written shorter chapters of 2-3K words. The issue? Twofold. First, when my writing tutor was reading them, he felt so immersed in the character and the world that the experience ended too quickly. The chapter just wasn't long enough to sustain his reading experience at the level he wanted.
Second, I have just two POVs in my debut novel, both written in close third-person. The chapters alternate: Character A, Character B, Character A, and so on. The problem here is that when you have a short chapter it can feel like whiplash to get through one quickly and then jump into another POV. This isn't so much of a problem with prose and narratives that are fairly simple and surface level, but if there's any depth, then you'll give your readers whiplash by using shorter chapters.
My chapters currently range from 5-12K words. Again, to the first point - it's epic fantasy, so readers sort of expect the length. But also, I specifically want to avoid POV whiplash!
Where did I learn this?
From direct, one-to-one lessons with my writing coach, who has over 30 years experience teaching creative writing, including at Oxford University, as well as a PhD in the subject.