What Counts as Square Footage? A Room-by-Room Guide
A space counts toward a house's square footage when it's finished, heated by a permanent system, reached from other living space, and has a ceiling of at least 7 feet. It also has to be above grade, so a finished basement gets its own line. Those are the rules appraisers use for what counts as square footage in a house, and they leave out garages, porches and decks.
The four tests a space has to pass
A room counts only if it passes all four tests below. North Carolina's Real Estate Commission spells them out in its residential square footage guidelines, and the ceiling rule matches Fannie Mae's summary of ANSI Z765-2021.
Walls, floor and ceiling built like the rest of the house. Bare studs or a bare concrete floor fail.
By a permanent system such as forced air or radiant heat. A fireplace or portable heater doesn't count.
Reached from other living space through a door or a heated, finished hallway or stairway.
Under a slope, at least half the room must reach 7 feet, and no part under 5 feet counts.
Above grade decides the rest. Fannie Mae treats a level as below grade if any portion of its walls is not entirely at or above ground level, so even a walkout basement is reported as below-grade area. See above grade vs below grade and the four basement types.
Appraisers call the total gross living area (GLA) and measure it under ANSI Z765-2021, which Fannie Mae has required since April 1, 2022. The ANSI Z765 guide covers the standard and what gross living area is covers the term.
Room by room: what counts and what doesn't
Closets, stairs and loft floors count; garages, porches and decks don't; sunrooms and attics depend on heat and ceiling height. Measure the rooms that pass, then add up several rooms into one total with the square footage calculator.
They sit inside the exterior walls, so they're already in the measurement. See do closets count.
Counted on the floor they descend from, so stairs to the second floor count upstairs. See do stairs count.
Screened, covered or open, they aren't finished, heated rooms. See porches, patios and decks.
A four-season room on the home's heating system counts; a three-season room doesn't. See does a sunroom count and Florida rooms.
Not even heated or drywalled. One fully converted into a finished, heated, connected room can. See does a garage count.
Below grade, so even a finished one is reported on its own line. See does a basement count.
Half the room needs a 7 foot ceiling, and the strips under 5 feet are left out. See does a finished attic count.
A loft's floor counts like any upstairs room. The open space over a two-story foyer doesn't.
Second floor, walls and ceiling height
Square footage adds up every finished, above-grade floor, includes the walls, and never multiplies by ceiling height.
A two-story house with 1,200 sq ft on each floor is 2,400 sq ft.
The tape goes around the outside of the exterior walls. Gross vs net square footage shows the gap.
It's floor area. Height only decides whether a space counts.
Buying flooring? Don't order from the listing. It includes the walls and leaves out the basement, so measure room by room instead. The flooring calculator does that and adds waste by material.
Why the listing, tax record and appraisal disagree
They're often measured by different rules. Fannie Mae notes that MLS and assessor figures "may not have been derived using the ANSI standard," and that appraisal square footage "is already often different from other sources."
When a number looks high, check for a finished basement rolled into the total, a garage that was counted, low attic space under 7 feet, or the air over a two-story foyer counted as floor.
To check a house yourself, measure each finished, above-grade floor to the outside walls and keep the basement separate. How to calculate square footage walks through the measuring, and the house calculator adds up the rooms.
Frequently asked questions
Does a screened-in porch count as square footage?
No. A screened porch isn't finished or heated by the home's system, so it's left out like open porches and decks. Enclosing it, finishing it and putting it on the home's heat can change that.
Are closets included in the square footage of a room?
They're included in the house total automatically, because the measurement goes around the outside walls. For one room's flooring, measure the closet as its own rectangle and add it.
Do stairs count as square footage?
Yes, once. Under ANSI Z765, a staircase belongs to the floor it descends from, so a flight between the first and second floors is counted on the second floor.
Does a heated garage count as square footage?
No. Heat alone doesn't turn a garage into living area. It would have to be converted into a finished room with a 7 foot ceiling, on the home's permanent heat and opening into the house.
Does a 4-season room count as square footage?
Yes, if it's heated by the home's permanent system, finished like the rest of the house and reached directly from it. A three-season room without permanent heat doesn't count.
What is heated square footage?
It's the finished living area served by a permanent heating system: the same finished, heated, connected space, though appraisers also leave out below-grade levels. North Carolina's real estate commission calls it heated living area and leaves out garages, porches, decks and unheated rooms.