Hello how may I help you? Hello I much space would I need in my apartment for a pet cat What kind of cat is it? It's a Persian cat They are low energy so 600 square foot should do. What would you recommend for an high energy cat 800 square feet. Why the extra 200 square feet? They are more energetic so they need more space to run around. I understand 600 square feet should be fine thanks Alright, glad I could help.