No one is sure where all those square feet developers advertise during the sales pitch disappear to when the studs go up, but one guess is in builders' pockets. The excuse for this problem used to be that no standards existed for measuring square footage in new homes. It's hard to justify the rationale that spaces outside the home, such as decks and patios, should be included in square footage but some developers have done just that. A common standard was approved by the American National Standards Institute in 1995, but it has been largely ignored by the industry. One useful exercise in examining brochures and marketing materials for developments is to do your own rough calculations.
Developers routinely lie about total square footage - and provide accurate room dimensions.
Take the time to multiply room dimensions and add the totals. Realizing that awkward corners and curves and some areas legitimately open to debate may skew your calculations, compare your amount with the developer's number. Because of vast disparities in measurement, figuring out the price per square foot is not a good tool of comparison, but it may be helpful in other ways. If either of the last two items are true, you might question what you're investing in. In buying new construction, it's often best to be early or late.