Why square footage is important

There are plenty of reasons you might want to know how to calculate the square feet of a house, whether you’re looking to sell a property, dispute a high tax assessment or renovate to add more space.

If you’re preparing to list your home for sale, determining the property’s exact size is a crucial factor when setting your asking price. “For a home appraisal, we’re going to compare it to comparables or ‘comps,’” says Day, who looks for homes of similar size in the immediate area. An inaccurate square footage measurement could potentially result in an inaccurate appraisal price.

Square footage (often abbreviated as SF or SQFT) also matters in real estate deals that involve a mortgage, for similar reasons. The lender will want that info to verify what the property is worth.

However, knowing your home’s square footage can come in handy in other ways as well. For instance, if you decide to finish a previously unused part of your house — say, a basement or attic space — you may need to provide the square footage to obtain a building permit.

Likewise, if your county or municipality assesses higher taxes than what you think you should owe, confirming the square footage can be a point in your favor toward getting the property taxes reduced.


How to Measure Square Footage of a House

Here is an overview of how to calculate the square footage of a house.

  1. Assemble your supplies. Bring a calculator, a tape or laser measure, a pen, and a notebook when you plan to measure the square footage of a space. You can draw out the floor plan with the notebook, measure the space with your tape measure, and add up your measurements with the calculator.
  2. Measure the separate areas of the house. Go through your house and measure the dimensions of each room one at a time. Measure a room’s length and width along the walls of each room in feet and note the metrics in your notebook.
  3. Calculate the square footage of each room. If you’re working with square or rectangular rooms, you can simply multiply the length of each room by its width to calculate the square footage. For irregular rooms, divide the space into geometric shapes, use the applicable formula, and add up the square footage. To measure the square footage of a triangular space, multiply its base by its height and divide that number by two. To calculate the square footage of a circular space, measure the circle's radius (the distance from the center point to the circle's edge), multiply that number by itself and then multiply the new number by pi (3.14).
  4. Add up the square footages of each room. Once you have the measurements of each room, add them all together to get your overall square footage. You can make the calculations yourself or use an online square footage calculator.


Count only those areas that are “inhabitable” according to ANSI standards. Inhabitable portions of a house include rooms with walls, ceiling and floor. These areas must be finished and heated or otherwise conditioned. Do not include spaces like patios, porches or garages. Also, if the house has an area with a vaulted (two-story) ceiling, do not count the open area as part of the second-story square footage.

What about stairwells and closets?

Any space that has walls, flooring, ceiling and heat would count as finished square footage. So, it’s likely that stairwells, closets, walk-in pantries and other areas you might be questioning would contribute to the square footage count of a home.

Tips For Determining Square Footage

There are some tips you could follow to make measu

There are some tips you could follow to make measuring the square footage of your home easier.

  • Push furniture to the middle of the room to make it easier to measure at the walls
  • Measure at the floor
  • Use a reel measuring tape. They are longer and easier to use.
  • Think in terms of squares and rectangles. For example, measure the square of a bedroom. Then, measure the closet.

Square footage and the MLS

One way to find out more information about a home you’re interested in, including square footage, is through information from the Multiple Listing Service (MLS). The MLS is a service real estate agents use to publish their active property listings so that consumers and agents can search for-sale homes and view them online.

Each MLS has different rules on how to report and what counts as finished square footage, but they all seek to standardize housing data so that you have the most accurate information and can trust the listings you find online.

What to leave out

A good rule of thumb to ensure you’re taking proper measurements is to exclude space you can’t walk on or live in. These types of spaces do not count as “gross living area.”

“Someone might think, ‘If I get the measurement of my first floor and I have a two-story house, I just multiply that by two,’” Day says. However, if that first floor includes a two-story foyer, you can’t count the non-usable space.

Basements and garages, even if they are finished, don’t generally count toward total square footage. Basements are typically excluded because they are built below grade, meaning below ground level. If your state does allow basements to be included in the total square footage of a home, though, you’ll likely need an ingress and egress, or a safe way to enter and exit the basement to the outside.

Finished attic spaces — with some regulations, including ceiling heights — can count toward the total square footage of your home. If you are planning to sell your home, work with a real estate agent to craft a listing that accurately reflects your property.

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:

Source: (Sergey Zolkin/ Unsplash)
Source: (Sergey Zolkin/ Unsplash)

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.

4. What is Net Cleanable Square Feet?

Net Cleanable Square Feet (“NCSF”) is the sum of a

Net Cleanable Square Feet (“NCSF”) is the sum of all floor area that requires custodial services. NCSF is a great metric to know, especially for your facility’s custodial personnel. Having accurate NCSF measurements can help determine custodial staffing, inform budgeting and aid in service provider solicitation.

Custodial budgets will realistically contain chemicals, paper supplies, equipment and custodial labor costs to get the job done. Not knowing your facility’s true NCSF might mean that you are budgeting too little or too much for cleaning. If you want to learn more about custodial budgeting and planning for your facility teams, check out our free guide on creating a custodial cleaning plan.

How to Calculate Net Cleanable Square Feet

Determine the square footage of each room that needs to be cleaned. Areas that require no cleaning, such as closet areas and mechanical rooms, should not be included. Once you’ve gathered square footage (minus non-cleanable areas) for all rooms, add them together. This number is your total square footage that needs to be cleaned.

You can take this process a step further and add cleaning costs to the equation. Multiply total cleanable square footage by a base price for cleaning. For instance, if your total area to be cleaned is 5,000 square feet and the price per square foot is 25 cents, you can multiply $0.25 times 5,000 to get a total of $1,250 for cleaning fees.

What Is Included In The Square Footage?

In measuring the square footage of a house, it is crucial to know what can and can’t be included in the calculations. Not every foot of your home enclosed by walls will count towards total square footage. Instead, you are trying to determine the gross living area — or the livable parts of your home. Keep reading to learn more about the specifications for measuring square footage:

Height Requirements

There is one measurement far too many inexperienced “appraisers” forget about: ceiling height. That’s not to say you measure the area as a three-dimensional space, but rather that the ceiling is one of the criteria I already alluded to. You see, for an area’s square footage to count in the home’s overall square footage, the ceiling above it must be a certain height. According to ANSI’s American National Standard For Single-Family Residential Buildings, finished areas must have a ceiling height of at least seven feet, “except under beams, ducts, and other obstructions where the height maybe six feet and four inches.” On the other hand, Angled ceilings must rest at the previously discussed seven feet for at least half of the room’s total floor area. If the ceiling is at least seven feet for at least half of the room’s floor area, total square foot calculations should include every area where the ceiling is at least five feet tall.

Garages, Protrusions, and Unfinished Areas

No matter how much you may wish your garage was included in the total square footage of your house, it’s not. I repeat, garages are not included in the total square footage of a property, even if they are finished — that’s because they are not the same level as the home itself. Similarly, chimneys and window areas are not included in a home’s square footage; not only are they not finished, but they are not on the same level.

Finished Home Connections

If you have a finished area connected to the house by a finished hallway or stairway, the subsequent area may be included in the home’s total square footage. However, finished areas connected in any other way (like by an unfinished hallway or staircase, for instance) won’t be included in the home’s total square footage.

Basements & Attics

Basements do not typically count towards a home’s gross living area regardless of whether they are finished. Since they are below the rest of the home, basements can’t be included in the total square footage. That said, homeowners may note the size of a finished basement in a respective listing elsewhere. On the other hand, attics may be counted in a home’s total square footage if they are finished and meet the height requirements stated above.

Covered, Enclosed Porches

Covered, enclosed porches may be included in a home’s gross living area if they are finished, and they are heated using the same system as the rest of the house.

Ask The Pros

Learning how to calculate the square feet of a house can be a challenging task. Thankfully, there are experts to help you. It is common practice to hire a professional appraiser to accurately measure your home. Depending on the property’s size, the cost of an appraiser to measure the square footage can range from $100 to several hundred dollars. When an appraiser calculates the square feet of a house, they also only include areas that are heated and cooled. While two different appraisers will sometimes have different measurements on square footage, there is usually only a 1-3% variance. Appraisers will do their best to calculate square footage with scientific accuracy.

Robert Reffkin

Robert Reffkin, the founder and CEO of Compass, helps you get closer to finding your dream home by simplifying and demystifying real estate.

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