Hello, how may I help you? Can you tell me how big my apartment needs to be for a pet cat? Your apt needs to be 10 feet for a pet cat. 10 feet high? 10 square feet. no kidding. So I could keep a cat in a prison cell? If you'd like too, you may. Will 2 cats fit in a 10x10? yes 2 cats will fit in a 10x10 space. Could you put a plethora of cats in a 10x10? Yes, a plethora of cats could fill a 10x10 space. Great. Time to go shopping. Thank you. You're welcome.