Examine the home's listing if you're the buyer. The multiple listing service or the brochure should spell out both the seller's asking price and the property's square footage.
For homes without a listed square footage and for previously sold homes, telephone the county tax assessors' office. Ask how you can access the property's tax records. Tax records are public documents that specify the square footage of the home's living space. Many counties make such records available online.
Make a list of all the nonliving space in the home. Nonliving space includes enclosed porches and patios, attics, garages and detached structures such as guest houses that you have to leave the property to access. As a rule of thumb, a room that is not heated is nonliving space. These spaces are not taken into account when calculating the fair market value of a home.
Add together the square footage of all the nonliving spaces. Deduct the total from the home's overall square footage. The resulting figure is the home's living space square footage.
Insert the home's sale price and living space square footage into the following formula to figure out the home's price per square foot:
Price/square feet of living space=price per square foot.
So, a 1,850 square-foot home listed at $350,000 has a price per square foot of 350,000/1,850=$198.19. At the time of publication, the median price-per-square foot of homes in the United States is $118, though large variations exist among states and neighborhoods.