I think one of the easiest solutions to this (since there really is no right and wrong, technically) is to get ahold of several novels similar to the one you're writing (similar in genre, tone, etc.), take a look at how they did it and average it out. But even then, I'd still just use it as a guideline. As others have said, chapters can be as short as one word or as long as the entire book. Last year I read Whiskey Sour by J.A. Konrath and while most of his chapters were fairly uniform in length, he had one that was about a paragraph long. As it turned out, that "little" chapter was the most powerful one in the book.