Too long: reader starts going "where is the end already"
Too short: reader goes "WTF?" when they see the chapter is over....
Seriously, its about that arbitrary

Some novels are broken into hundreds of little 1-2 page chapters, others into just 3-4 ginormous ones, while many float somewhere in between. It depends on genre, pacing, etc. Suspense novels and thrillers, for example, tend to go with shorter chapters to match the faster pace, while romances and fantasy often have longer ones. A general guideline is that each chapter should center around a single event or setting in the novel, that may or may not span multiple scenes. Folks often end chapters at a crucial moment, as well, so readers are inclined to continue on to the next rather than go "good stopping place."
It might help to study some of your favorite novels in the genre you're writing to see hot they did it, but in the end go with your gut. And yes, you're right, once you're done and into the editing, you'll likely rewrite, remove words, add words, and shift the chapter divides and even whole chapters around all together.
