It seems something as concrete as square footage shouldn’t be up for interpretation. It’s math. There should be one correct answer, right?
… But it’s not so simple. It’s variable and complicated and there’s more than one way to do it.
Measure the Square Footage of a House Yourself
Fortunately there are some general rules. If you want to measure the square footage of a house yourself, here are a few guidelines:
Grab a piece of graph paper and sketch out the layout of your home. Create a separate drawing for each floor. This doesn’t need to be to scale and you don’t have to be a Pictionary champion.
Though you might be inclined to just pace out the rooms and call it day, estimating to this extent won’t get you anywhere good. This project was made for a tape measure.
To take you through the steps, let’s use this obscure architectural wonder as an example. OK, fine, it’s no Frank Lloyd Wright but it works for this purpose!
1. Divide the house into shapes. Rectangles and squares are easiest and most common, but maybe you have a circular breakfast nook, or a triangular closet under the stairs.
2. Measure the length of each wall and write down the dimensions. For the circular room, measure the length across (diameter). And for the triangular room, measure the length from one corner to its longest side.
3. Do some geometry. (You thought you’d never use this stuff again, huh?)
Here’s how you find the area for each of the rooms:
For rectangular and square rooms:
Area = Base x Height
Blue room = 22 feet x 10 feet = 220 square feet
It’s easiest to treat the green room like two rectangles.
Green room =
- 20 feet x 10 feet = 200 square feet
- 14 feet x 5 feet = 70 square feet
For circular rooms:
Area = π x Radius2
Radius is half the diameter = 7, and one-quarter of the circle is gone.
Yellow Room = 3.14 x 49 = 154 sq ft x .75 = 116 square feet
For triangular rooms:
Area = (Base x Height) / 2
Purple Room = (14 feet x 7 feet) / 2 = 49 square feet
4. Add them together. Once you have the area for each room, add them all together to get the total square footage.
For this house = 220 + 270 + 116 + 49 = 655 square feet
Hire a Professional to Measure the Square Footage of a House
That seems like a lot of work, you’re saying to yourself. The good news is that you don’t actually have to do it yourself. In fact, you shouldn’t, at least not in an official capacity. It’s nice to be able to estimate, double check and generally know what counts and what doesn’t, but when it comes to putting your house on the market, it’s important to get a professional.
Angelina Keck, a top-selling agent who ranks in the top 1% of agents in Houston, says you should call an appraiser and ask for a measure. It’ll cost you about $150. “They’ll put their stamp on it so it’s official. This is the best and most reliable way to estimate square footage.” An appraiser will likely take measurements from the exterior.
You should hire an appraiser to measure because:
You might count something that doesn’t count.
Square footage gets a little murky. Areas like your patio, your garage, your basement and your attic… even though they are clearly parts of your home, are not necessarily considered part of your “gross livable area” (GLA). There are some exceptions to this though.
- Your garage doesn’t count as part of your square footage.
- If your attic has seven feet of ceiling clearance and it’s finished, you can count it.
- A good litmus test for whether an area counts as GLA is whether the room is heated or cooled by the same means as the rest the house. If your house is on central A/C but your enclosed patio has a swamp cooler, you can’t count the patio in your square footage.
- Basements are only sometimes counted. It depends on the area, as well as if it’s finished or not. (Is it mostly old boxes, or does your son live down there?)
Say you measured everything yourself and you tell your Realtor that your house is 2,200 square feet. She puts this into MLS. It’s highlighted on your house flyers. It’s plastered across the internet. Eventually, someone puts in an offer. But during the vetting process, their appraiser comes up with a lower number — only 1,600 square feet. Uh oh.
You counted your giant garage in your measurement and now the sale could fall through because their offer was based on a 2,200-square-foot house. A good agent will look for that appraiser stamp, but it’s still good to look out for yourself too.
You can’t always depend on tax documents.
Why pay to have someone measure when your tax documents already have your square footage? Because you can’t always trust what they say. When builders make plans, they send them to the county assessor. As a development sells (or doesn’t), builders and architects may make adjustments to those floor plans but they don’t necessarily update the city. This means tax reports sometimes reflect the wrong square footage for houses.
You might already have all the information.
Don’t sign up for more work than you have to. If this isn’t the first time your home has sold, someone had to have an appraiser measure the last time it sold. Locate that report. Unless you constructed an addition, that appraiser stamp on the measure is still accurate and valid.
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