Word Count for Children's Books

A beginning writer recently asked me about the word count of children’s books. No specific answer qualifies for every publisher, but here is a general overview: 
Board books: 0-100 words. 
Fiction picture books range from 0 to 500 words. These books keep getting shorter. Nonfiction titles are often longer. 
Early chapter books for 5-7 year-olds are illustrated and range 1,000-7,000 words. 

Chapter books for the older audience, ages 7-9, range up to 15,000 words.    Middle-grade novels for ages 8-12 are usually between 20,000-45,000 words, maybe more. My middle grade novel, AMAZING GRACE, topped out at 33,000. 
YA (Young Adult) novels range higher: 50,000-85,000. 
Publishers set their own parameters for word length. There are many variations, but these are generally acceptable. 
Nancy Kelly Allen has written 40+ children’s books and a cookbook, SPIRIT OF KENTUCKY: BOURBON COOKBOOK.