Hello how may I help you? Can you give me some pet advice? I can give you pet advice. How much space does a cat need for an apartment? A cat needs approximately 300 square feet. Does that include a play house? I want to make sure he's happy. That includes all accessible space. If I adopt a second cat, how much space will I need then? Adding a second cat will require a total of 600 square feet of space. Perfect, thanks for your help! You're welcome.