How to calculate the square footage of a house (2024)

Most of us probably care about the square footage of a house when we’re looking to buy because it tells us how much house (i.e., livable space) we’re actually getting. But square footage also impacts your tax assessments, home insurance, and even getting permits for renovations.

If you’re measuring square footage to find out how much livable space your house has, you’ll want to take interior measurements. By measuring from the inside wall, you can get a better sense of whether or not the space meets your needs. For example, you might have a sofa that needs a certain length of wall space. If the room doesn’t have it, the sofa won’t fit.

The steps for calculating the square footage of a house are:

  1. Sketch each room of your house. Plotting out every room of your house, including hallways and closets, can help you tally your square footage as you go
  2. Measure the length and width of each room. Use a measuring tape to measure the length and width of every room in feet. This is easy when the room is rectangular or square. However, if you have oddly shaped rooms, you may want to use an online square footage calculator.
  3. Multiply the length and width. For example, if your living room is 20 feet by 15 feet, its square footage is 300 square feet. Note each room’s measurement on the sketch you created in the first step.
  4. Add room values together. Take the totals from each room and add them together to get the total square footage of the house. This is the usable space in your home and may be different from an appraisal or the country tax records.

If you have a room with nooks and crannies you may need to break it down into measurable rectangles. That way, you can get the square footage of the smaller spaces and add them all together for the room’s total square footage.

For example, let’s say that your living room is 10 feet wide, but one wall has an odd notch at the corner that protrudes one foot into the room, like the image shown below.

How to calculate the square footage of a house (1)

The best way to measure the square footage for that room is to divide it into two rectangles. The first rectangle starts at the edge of the notch and goes to the other wall, and the second is the rest of the room.

Some people make the mistake of calculating the square footage of a two-story home by measuring the bottom floor and simply multiplying that number by two. This can be accurate if the floor plans for each floor match exactly, but it’s incorrect for homes with two-floor entryways.

How is the square footage of a house calculated for an appraisal?

Most people who buy a house get an appraisal to determine its fair market value, and one of the appraiser’s tasks is calculating the home’s square footage. The process is often similar to what you would do to measure square footage. However, your appraiser’s calculation might not match yours or even what’s on the actual listing.

The most common reason the square footage may be different in your appraisal is that an appraiser needs to evaluate the total value of your home. As a result, the square footage in an appraisal may include nonliving spaces, like attics, unheated basem*nts, and open patios.

Your appraiser’s square footage calculation may more closely match what’s on county tax records, but that’s not always the case. For example, the square footage of a house may not be accurate on tax records if the owner encloses their patio without getting permits.

Is house square footage measured inside or out?

Whether a home’s square footage is measured by the interior or exterior depends on who you ask. An interior designer and realtors who need to determine the usable space may use the interior walls. Architects, however, may use exterior walls.

What is included in the square footage of a house?

Only usable space is included in your home’s square footage. Typically, usable space is defined as areas in your home that:

  • Share the same heating and cooling system as the main house.
  • Are located above ground.
  • Conform to your home’s architectural standard.
  • Are finished and adjoining.

Looking at it that way, it’s pretty clear that rooms like your kitchen, living room, bathrooms, and bedrooms are part of your square footage﹘as long as you don’t have to pass through unfinished spaces to reach them. The same goes for hallways, stairways, and closets. Enclosed patios may be included if they have four walls and a roof and use the same heating as the rest of your home.

A finished attic can also be part of your square footage, but like enclosed patios, it usually has to share your home’s heating and cooling system. Plus, it may need a certain amount of headroom to count.

Garage and basem*nts aren’t usually included in the square footage of a house. This is often true even if the basem*nt is finished because it’s below ground level. However, some states do allow you to include finished basem*nts when they have safe ways to enter and exit. Detached structures such as sheds are also generally excluded from the calculations.

Do closets count as square footage?

Closet areas are included in the square footage of a home, but only when they are in the main home. Closets in areas that aren’t considered usable space, like basem*nts, aren’t included. When you calculate the square footage of a house, treat each individual closet as if it were a room and add it to your total.

Square footage can be very important when it comes to buying or selling a home. Many buyers start looking with a particular number in mind, so having an accurate measurement can help get your home in front of the right audience.

However, Chief Real Estate Analyst and Managing Editor of The Close, Emile L’Eplattenier says that in some cases, other features can be more important than square footage. A good example in some markets is when developers decrease size in favor of amenities.

“While price per square foot is still a useful metric,” says L’Eplattenier, “developers of luxury buildings in Manhattan and Brooklyn have been decreasing average unit sizes for more than a decade now.”

Ultimately, homebuyers need to use the square footage of a house they’re interested in as one piece of information. It may tell them something about whether the house fits their needs, but they need to weigh other factors, like location and quality.

Square footage and home insurance

Insurance companies usually want to know your home’s square footage when you apply for homeowners insurance because they use it to figure out how much dwelling coverage you need. They need to know that you’re insured for what it would cost to rebuild your home from the ground up. Having accurate square footage helps both you and your insurer know that you are insuring your home properly.

How to calculate the square footage of a house (2024)

FAQs

How to calculate the square footage of a house? ›

If the property is a perfect rectangle, simply measure the length and width and multiply those two numbers together. For example, if your one-story house is 60 feet wide by 40 feet long, then your property is 2,400 square feet (60 x 40 = 2,400).

How do you calculate the square footage of a house? ›

As a buyer it can be helpful to know how to calculate the square footage of a house yourself – just multiply the length and width of all applicable rooms in the home.

What can you count as square footage in a house? ›

When an appraiser calculates the square footage of a home, it will only measure interior spaces that are heated and cooled. This includes bedrooms (and closets), bathrooms, hallways, a kitchen, living areas, enclosed patios, and finished attics.

How do you work out the square size of a house? ›

How to calculate house squares for your home
  1. Break down the area by room. Measure a room's dimensions (width and length), and multiply these together. Do this for each room, add them together, and you have the total square meterage of your home.
  2. Divide this figure by 9.290304 to get the number of squares.
Aug 8, 2023

How much square footage is enough? ›

How To Calculate What Size House You Need
Number of PeopleSquare Footage
1600 sq. ft.
21,200 sq. ft.
31,800 sq. ft.
42,400 sq. ft.
Oct 27, 2022

What is the formula for calculating square feet? ›

The next step in how to calculate square footage is to plug your measurements into the square footage formula: L x W = A (in square feet). How to find square feet: multiply the length measurement in feet by the width measurement (in feet).

What is the normal square footage of a house? ›

Average Square Footage of a House

The average house size is right around 2,500 square feet, but that doesn't mean you should aim for the middle and hope for the best.

What doesn't count in square footage of a house? ›

As for rooms in the house that aren't finished, like basem*nts or attics, they should not be included in the total square footage. In fact, any part of the house that is below ground level -- even if it is only partially so -- should not be included under any circ*mstances.

What is not included when the square footage of your house is calculated? ›

In general, areas like staircases and closets count as finished square footage. Spaces like garages, three-season porches and unfinished basem*nts or attics are not included in the square footage of a house.

Does the square footage of a house include both floors? ›

Square footage is measured per floor. Interior, or Livable square footage would be performed room-by-room. If the multistoried structure has a uniform exterior, then the quickest estimate can be done by measuring around the outside perimeter, then multiplying by number of stories.

How to calculate the built-up area of a house? ›

As per RERA, the built-up area includes the carpet area plus the extra areas certified by the authorities, such as the area of the outer and inner walls, dry balcony area, etc. Built-up area calculation: Carpet area + wall area + excluding balcony and corridor = Built-up area.

Do you measure the outside of a house to get square footage? ›

How to Measure Square Footage of Your Home in 4 Steps. The gross building area can be easily calculated by measuring the exterior walls of your home to calculate the area, and multiplying by two or more for additional stories. However, the most important measurement only looks at the space that's livable inside.

How to calculate square feet of a house with different sides? ›

To calculate the square footage of an irregular shape, divide the irregular shape into smaller shapes, find the area of each, and then add up all the results.

How is housing square footage calculated? ›

Measure the length and width, in feet, of each room. Then, multiply the length by the width to calculate that room's square footage. For example: If a bedroom is 12 feet by 20 feet, it is 240 square feet (12 x 20 = 240). For each room, write the total square footage in the corresponding space on your sketch.

What is the 5 foot rule for square footage? ›

According to the ANSI Guideline, to be included in the finished square footage count, rooms/spaces/areas are supposed to have a ceiling height of at least seven feet for over half of the space, and no portion of the finished area can have a ceiling height of less than 5 feet.

What is not included in the square footage of a house? ›

As for rooms in the house that aren't finished, like basem*nts or attics, they should not be included in the total square footage. In fact, any part of the house that is below ground level -- even if it is only partially so -- should not be included under any circ*mstances.

Does square footage of a house include all floors? ›

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.

Is the square footage of a house inside or outside? ›

Many professionals in the building and construction industry may report the gross square footage of a home, or the total footprint of the structure on the property, which measures along exterior walls.

Is the garage included in the square footage of a house? ›

The square footage of a house usually does not include the garage. Garages are considered separate from the main living space and are often evaluated and appraised differently.

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