Yes, there are guidelines to follow when it comes to the number of words in your children’s story. Remember, these are not hard and fast rules, but rather guidelines that I encourage authors to at least consider.
Here’s more information about various children’s book formats.
Board Books: These are for babies and toddlers. Generally, the copy is limited to one sentence per page.
Picture Books: This is a wide-ranging category, and as such, word counts vary considerably. Most picture books are twenty-four pages. Early picture books are typically less than 500 words. More advanced picture books are right around 1,000 words. I’ve seen fantastic picture books that are closer to 2,000 words, but there really needs to be a compelling reason to come close to, or exceed 2,000 words.
Early Chapter Books: What kid hasn’t proudly announced, “I’m reading chapter books now!” Graduating from picture books to chapter books is a milestone to be celebrated. Two popular early chapter series are The Magic Tree House and June E. Jones. Typical word count is between 5,000 and 12,000 words. This range works beautifully, so I urge you to stick to it.
Intermediate and Teen Reading: Most titles on middle school reading lists contain 30,000-40,000 words. And finally, there’s the teen novel category which my eleven year old daughter is devouring presently. (Aside: I still find it amusing that there’s a sub-category called “teenage vampire romance.”) Teen novels typically start at 45,000 words and the sky’s the limit from there.
I hope you find this information helpful. Remember, these are just guidelines.