So, we have 3 cats - Sushi, Smokee, and Buddy. And we live in a 600 sq. ft. duplex. Yes, a tiny space for 3 humans and 3 cats. We have a front yard and a backyard, with a nice little side yard. Nevertheless, we have 3 cats in a very small space. Yet, it doesn't even smell like we even have one cat! Every time we have someone