Nebula award define it as:http://www.sfwa.org/awards/rules.htm
Short Story: less than 7,500 words.
Novelette: at least 7,500 words but less than 17,500 words.
Novella: at least 17,500 words but less than 40,000 words.
Novel: 40,000 words or more.
Though SFWA cautions elsewhere (http://www.sfwa.org/writing/faq2.htm):
Q: How do you decide where the novella ends and the novel starts? Does life exist for a story between 16,000 and 60,000 words?
A: SFWA Nebula rules say a short story is 7499 words or fewer, novelette 7500-17,499, novella 17,500-39,999, novel 40,000 or more.
You're much more likely to sell a 20,000 word novella, though the market will always be tighter for them than for shorter works.
In children's books, though, a 30,000 to 40,000 word work can be a whole book by itself.
To sell a novel under 60,000 words to a genre publisher requires a novel that is extraordinary.
Q: So you have a story that is 40,000. Do you pad it to 60, chop it to 20, or leave it be?
A: If you can see a way to chop a 40,000-word story to half that length, or pad it to half again that length, it was either written at the wrong length to start with or it isn't much of a story.
If you can =continue= the story, on the other hand, you may end up with a strong 80,000-word novel in two parts or two books (not physical books, but 2 sections of the novel). Or take that 40,000-word story and carefully analyze it to see whether you might have rushed through a part, or whether there might be a subplot that could be developed with more leisure or detail. Don't pad it, because an editor will spot the treading-water part, and probably yawn and put the thing back in the SASE. But it's possible you missed a place where you could legitimately add 20,000 or so words.
It's not only difficult to sell a novel under 60,000 words, it's difficult for the publisher to push it once it's bought. You wind up with an $18.95 hardcover that's half the physical size of a $20.95 one.
If, however, this story can be told as a YA novel, you've got no problems with its length. YA and middle-grades novels are often 40,000-60,000 words. In fact, middle-grades novels can be shorter.
.....
For hard SciFi and high fantasy though, chances are you won't sell as a new author at less than 80k words. Because, if you think about it, a 500 page novel with 400 words per page is 200k words. Which is about average for hard SciFi and high Fantasy (unless it's a series in which case that's short past book 3).
For mainstream you typically go shorter. Big Fish, for example, sold very well, was turned into a movie, and is 208 pages with *maybe* 300 words per page (208*300=62k). The Stephanie Plum books are usually around 75k words. Stephen King's latest books (beside the Dark Tower) have all been around that size, or slightly larger too.
In the end a lot of it just depends on your market.
[This message has been edited by Jammrock (edited November 28, 2006).]
[This message has been edited by Jammrock (edited November 28, 2006).]