Animal Farm is considered a novella, which is shorter than a novel.
• Burmese Days (1934): 97000
• A Clergyman’s Daughter (1935): 94000
• Keep the Aspidistra Flying (1936): 87000
• Coming Up for Air (1939): 83000 (?)
• Animal Farm (1945): 30000 (just over 30k)
• Nineteen Eighty-Four (1949): 103000 (or 99000 without the “The Principles of Newspeak” appendix).