**To calculate cost per square foot, divide the purchase price of a house by its total square footage.** For instance, if a house with 2,000 square feet sells for $180,000, the cost per square foot is $90 per square foot.

Cost per square foot can also be determined for rental property. Divide the amount of the annual rent by the number of square feet. For instance, a 1,000-square-foot property that rents for $10,800 a year costs $10.80 per square foot. In rentals, square footage sometimes includes a portion of the spaces available to all tenants, such as lobbies and hallways. On the other hand, "usable square feet" refers only to the square footage within the walls of the leased area.