Cities in Florida, Texas and Arizona dominate the list. : The average size of new apartments in the U.S. in 2018 is 941 sq. ft., 5 percent smaller than 10 years ago. Seattle has the tiniest apartments in the country, with an average size of 711 sq. ft., Manhattan and Chicago the second smallest rentals, 733 sq. ft., while Tallahassee, Fla., offers the most largest rentals at 1,038 sq. ft. The largest share of apartment dwellers, millennials prefer living in locations close to restaurants and entertainment rather than having a large kitchen or living room to cook or entertain at home.