Novelist Jane Smiley suggests that length is an important quality of the novel.[1] However, novels can vary tremendously in length; Smiley lists novels as typically being between 100,000 and 175,000 words,[2] while National Novel Writing Month requires its novels to be at least 50,000 words. In part because of this wide variation, the boundary between a novella and a novel may be arbitrary and difficult to determine.[3] But while the length of a novel is to a large extent up to its writer,[4] lengths may also vary by sub-genre; many young adult novels start at a length of about 16,000 words,[5] and a typical mystery novel might be in the 60,000 to 80,000 word range while a thriller could be over 100,000 words.[6]The Science Fiction and Fantasy Writers of America specifies word lengths for each category of its Nebula award categories:[7]Classification Word countNovel over 40,000 wordsNovella 17,500 to 40,000 wordsNovelette 7,500 to 17,500 wordsShort story under 7,500 words