The New York Times published an informative cover storyon how the quoted square footage of apartments is frequently “exaggerated, massaged, misrepresented and manipulated.”       I have noticed for years that sellers and landlords routinely overstate square footage. I would estimate an average embellishment of over 10 percent.          According to appraiser Jonathan Miller, the square footage of an apartment is determined by measuring the space between the interior walls, including bathrooms, closets and foyers. Outdoor space should not be included in the total square footage or should be quoted separately from the interior space.         Condominium offering plans are required by law to disclose the square footage of each apartment but should still be checked for accuracy. For example, the offering plan for 1420 York Avenue Condominium lists all 99 studio apartments at 400 square feet even though they range from under 350 to about 450.          Most cooperative offering plans publish only floor plans with room dimensions.          Determining the square footage of an apartment, then, is not that difficult. Simply follow these three steps:          • Verify with a tape measure that the published room          dimensions are accurate.      • Cut and paste the floor plan into a PowerPoint slide     • Use the PowerPoint ruler and a bit of basic geometry and        algebra to determine the total area.        Overstating square footage is a frequent source of lawsuits against brokers and their clients. In 1998, most famously, a couple purchasing a $2.5M “classic six” apartment at 983 Park Avenue sued Stribling & Associates for the return of their down payment plus $25,000 in legal and architectural fees. The purchaser had discovered that the apartment was only 2800 square feet while the marketing materials had represented 3300 square feet. The case was settled out of but could have been avoided had the square footage been accurately represented accurately or not represented at all.         The square footage misestimates are a self-perpetuating phenomenon. Square footage is perhaps the first metric that buyers and their agents examine while scanning and sorting listings. Thus, sellers and agents do not want their units to be perceived as smaller than similarly sized listings. If your apartment is really 450 feet, but all the competing listings are overstated at 500 – 550 square feet, then prospective purchasers will overlook your listing.         Another explanation is that dollars per square foot is the most frequently cited metric when casually valuing apartments. Squeezing out an extra 50 square feet by including hallways or measuring from outside the exterior walls might justify a 10 to 15% increased in perceived value. Phrases such as “pre-war co-ops west of Third Avenue are selling for 1100 square feet” are common in this industry.          The inaccuracy of quoted square feet is just one reason why I think that dollars per square feet should be de-emphasized as a measure of value, particularly for co-ops. When used uncritically, the metric also fails to account for differences in light, views, condition and maintenance charges.          The overstating of square footage has been going on so long that most people misperceive apartment sizes. For the uninitiated, here is my guide matching square footage with apartment size:          300 – 350: Small Studio       400 - 450: Average Studio     525 – 550: Large Studio – Alcove Studio     600 – 650: Small 1BR     700 – 750: Standard 1BR     850 – 950: Junior 4     1000 – 1100 Small 2BR     1200 - 1400 Average 2BR – Small 3BR     1500 – 1800 Standard 3BRs and up       For condominiums, I would advise selling agents to quote the square footage cited in the offering plan. For coops, I would use only the room dimensions listed in the offering plan. I would double check everything with a tape measure and include unambiguous disclaimers.          Finally, buyers making the largest purchases of their lives should also take it upon themselves to double check all measurements.          While square footage remains a contentious issue in residential estate, I’ll save the even more dubious claims and ambiguities common in commercial real estate in another article.