What's the "average book?" A short novel, like Arthur Conan Doyle's The Hound of the Baskervilles, has about 60,000 words. A huge doorstop of a book like Ayn Rand's Atlas Shrugged has more than 500,000 words. The advice you'll see most often on this forum is that your first novel, as an unknown writer, should be in the range of 80,000 to 120,000 words. Publishers prefer it that way.
Thrillers and mysteries usually clock in under 75,000. High epic fantasy push 100,000 frequently. Romance novels are usually around 45,000-60,000 words, smaller novellas exist as well such as the popular 100 page ones. There is really no hard or soft cap for word count, the bigger the plot the bigger the book. Also averages typically are some middle ground between the high and the low, even though a few number of books are probably fall within the average of 80,000.
To expand on the person above my post said: Epic fantasy: 90,000- A song of ice and fire (look it up, the books are like bricks) Romance: 65,000- 80,000 Thrillers: 65,000- 80,000 Young adult fiction: 60,000- 100,000 Science fiction: 70,000- 100,000 Mystery: 55,000- 70,000 The reasons for the word counts are different for each genre. Thrillers need a fast pace novel so everything will be happening quicker, therefore less words. Romance is also a smaller book, but because the plot is usually rather linear and more about the characters then the depth. Epic fantasy is the opposite, as it will have slow points and fast points and are usually very complex with tons of characters and a huge plot. Mystery is small because there is only so many twists and turns you can do before the reader wants to know who is the killer. Young adult fiction is a little different because it can be YA-fantasy or YA-Science fiction, but I included it because it often is smaller then normal adult books. For example, an average fantasy book might be 120,000 words, but YA fantasy book would probably be 90,000-100,000 (look at Percy jackson, Harry Potter).
I consider 'To Kill a Mockingbird' an average novel in terms of word count. 376 pages 100,388 words =267 words per page That's the number I'm going for, 100,000 words.
Around 100,000 is the norm for novels nowadays. But I wouldn't worry too much about word count when writing a novel. Just make sure you're developing everything to the best of your ability. If you have a complete novel that is everything you could have dreamed of and it's only 84,000 words, don't inflate that number just because it seems low. If you go that route, you better believe that your editor will end up chopping most of that crud out anyway...
