Here's what Litereary Rambles have to say about it
Board Books: 0 - 100 words.
Early Picture Books: 0 - 500 words.
Picture Books: 500 - 1,000 words. Less is more as the pictures do the talking.
Nonfiction Picture Books: 500 - 2,000 words.
Early Readers: 200 - 3,500 words, depending on age level.
Chapter Books: 4,000 - 10,000 words.
Young Adult: 45,000 - 70,000 words.
Nonfiction MG/YA: 5,000 - 70,000 words
And here's another point of view.
- Board books. These contain very few words- no more than 100 total.
- Picture books. Generally, between 500-700 words (although it's much easier to get a 500 word picture book published) in a standard 32 page count.
- Early readers. e.g. Dr. Seuss, Between 1,000 and 4,000 words.
- Chapter books. Between 5,000 and 15,000 words long
- Middle grade novels (ages 8-12). A typical word count of 25,000 to 40,000.
- Young adults. (ages 12+) Average 50,000 to 70,000 words, There are always exceptions - e.g. Eragon - but the guy's parents did own the publishers!
Comparing both, there are some differences but roughly the same. Though as ever in this industry, nothing is set in stone. Stephanie Mayer herself admits the fact that had the assistant literary agent not known that 130,000 words was a bit long for a young adult book, the agent who ended up taking her on would not have looked twice at it!
Some publishers will give you a rough guidline as to what they are looking for. But most of them won't bother - assuming that anyone worth looking at will have researched it for themselves and know what they are doing!
Best Picture Book of the moment;