There is no one answer. I will use middle grade and young adult for my examples.
Chuck Sambuchino, editor for Writer's Digest Books wrote the definitive post on word count for novels and children's books.
MG - 20k - 45k
YA - 55k - 70k (add 5k for fantasy/sci-fi)
Colleen Lindsay from Fineprint Literary Agency, posted this entry on word counts and novel length.
MG - 25k - 40k
YA - 50k - 80k (longer for paranormal or fantasy)
Nathan Bransford from Curtis Brown, Ltd, posted this entry on novel word count. He's not a stickler for word count. In his words, "If it works, it works." His larger point was that agents will reject you outright if your word count is outrageously high.
Kristin Nelson of Nelson Literary Agency posted this entry on the word count question. She points out that it's the completely wrong question to ask. The right question is to ask how important pacing is in your novel. Length won't matter if the pacing of the novel makes it such that the reader doesn't care. Case in point: Harry Potter & Twilight. (among many others I can think of). She would know. She sold Helen Stringer’s Spellbinder, which my daughter, wife and I recently enjoyed.
On the flip side, Michael Bourret of Dystel & Goderich Literary Management posted this query critique on a relatively short middle grade novel. (28k words). He wasn't worried about the word count, thinking that they could expand the book in the editorial process if need be.
To complicate matters, in my research I found an agent or two that categorized some well known middle grade novels as young adult. These are definitely MG books - they're shelved with MG, the characters are middle schoolers, and the themes are very much MG. Yet, those novels had 80k word count. If you were to query such an agent with a middle grade novel of 40k words, would they think twice when reading the query letter?
In the end, I think you tell the story that's in your head. Then revise the heck out of the thing - lop off what doesn't move the plot along. Ensure the pacing is appropriate for your target audience. Get people to read it and make sure it's just right. When you're done and you think it's right, if it falls well outside the typical range for your genre and target audience, you have a decision to make. You can query anyway, but keep in mind that you're lowering your chances overall. As you can see above, some folks are less concerned than others. Remember that publishing is a business. And if the story is just right, decisions made based on word count are often driven by the business side of things, especially for debut authors.
On the flip side, Michael Bourret of Dystel & Goderich Literary Management posted this query critique on a relatively short middle grade novel. (28k words). He wasn't worried about the word count, thinking that they could expand the book in the editorial process if need be.
To complicate matters, in my research I found an agent or two that categorized some well known middle grade novels as young adult. These are definitely MG books - they're shelved with MG, the characters are middle schoolers, and the themes are very much MG. Yet, those novels had 80k word count. If you were to query such an agent with a middle grade novel of 40k words, would they think twice when reading the query letter?
In the end, I think you tell the story that's in your head. Then revise the heck out of the thing - lop off what doesn't move the plot along. Ensure the pacing is appropriate for your target audience. Get people to read it and make sure it's just right. When you're done and you think it's right, if it falls well outside the typical range for your genre and target audience, you have a decision to make. You can query anyway, but keep in mind that you're lowering your chances overall. As you can see above, some folks are less concerned than others. Remember that publishing is a business. And if the story is just right, decisions made based on word count are often driven by the business side of things, especially for debut authors.
