What is the correct word count for a book in the genre of Ella Enchanted?

Harry Potter and The Deathly Hallow is 784 pages long. There is no clear cut line for word count and genre. You may find lots of varying information that will leave your head quite confused. It is true that nowadays middle grade titles are quite longer than they used to be. You may write a long book that may need to be shortened- or you may write a shorter one that the editor thinks may need lengthening a bit. There will be changes made to your book no matter what you do. So unless you have specifications set out by agent regarding book length and genre, just press on and write your book and good luck!