When doing freelance writing, there are so many rules. These standards are not etched in stone and may be subject to change, in case you didn't pick up why I used such as my post title.
Peruse my below list I gathered from search engine research but know that different publishers have different standards and guidelines. And remember! This Is Subject To Change.
Short story - 1,500 to 30,000 words
Novelette - 8,001 - 17,500 words
Novellas - 30,000 to 50,000 words
Novel - 55,000 - 300,000 words