Understanding your home’s square footage requires more than just geometry

All square feet are not created equal. Even Thomas Jefferson would have agreed. There are basements. There are attics. There are garages remodeled into living spaces, and there are oversized storage rooms locked in remote, poorly accessible corners.

But when it comes to calculating a home’s square footage, we are left with a number — a simple number often relied upon to estimate a home’s value, cost to construct and overall livability. So it is worth understanding exactly what those simple digits represent. How are they calculated? What rules are used to figure it accurately, and what are the potential flaws in the venerated number known as the square footage of a home? Here’s how to calculate square feet.