couple measuring brick wall

How To Calculate Square Footage Of A Home + Calculator

Miranda Crace3-Minute Read
August 12, 2022

Knowing how to calculate the square footage of a space can help you determine your home’s value, install flooring or evaluate the cost of painting the house.

Our square footage calculator makes it quick and easy to estimate the square footage of a lot, room or an entire house. For more complex spaces, you can get a better estimate by breaking it down into several simple shapes and adding their square footage together.

Square Footage Calculator

When using a square footage calculator, you can estimate the size of a lot, a room, or even an entire house. But it’s important to know that for more complex spaces, you can often get a better measurement estimate by breaking it down into several simple shapes and then adding their square footage together.

Use our square footage calculator to estimate the size of any space in your home:

How To Calculate Square Footage

Square footage of rectangular spaces is most common and easy to calculate with this simple formula: area = length x width.

How To Calculate Square Footage formula

But not all homes are strictly square or rectangular. Formulas vary depending on the rooms shape.

  • Circle: Area (ft. X 2) = Pi x (diameter/2)2
  • Triangle: Area (ft. X 2) = √[(a+b+c) x (b+c-a) x (c+a-b) x (a+b-c)]
Square Footage Of a Circular Room formula
Square Footage Of A Triangular Room formula.

What’s Included In Square Footage?

Anywhere with flooring, wallcoverings and ceilings that can be lived in daily will be included in square footage.Unfinished basements and attics should not be included in a house’s total square footage. But it can be counted if an attic or loft space is finished and accessible by stairs.Basements can be tricky. Even if a basement is finished, its area should not be added as part of the house’s total square footage, as any part of a home that falls even partially below ground level should not be included in the total square footage.Garages should also not be included in the calculation of total square footage. If a house has an attached garage, the shared wall will act as the outside wall of the house when determining square footage.While the American National Standards Institute (ANSI) encourages you to measure the exterior of your home's square footage, that method does not subtract wall space and does not give an accurate measurement of living space.

Square Footage FAQs

What Is A Square Foot And Why Is It Important?

A square foot is a measurement of any two-dimensional surface. It’s equal to a square measuring 1 foot on each side. However, square footage is not a measurement reserved only for square spaces. The most accurate way to determine the amount of habitable space in a homeowner's property is through square footage.

How Many Square Feet Is A 10 x 10 Room?

A 10 x 10 room is 100 square feet. Since it is a basic square, you can easily find the square footage by multiplying the length (10 feet) and width (10 feet).

Why Does Ceiling Height Matter When Determining Square Footage?

While you’re not finding the three-dimensional area of a room, the ANSI states that your ceiling does need to be at least 7 feet for over half the home, and no portion of the finished area can be less than 5 feet to be included in a house’s square footage. Because of this, crawl spaces cannot be included.

Why Do Painters Base Their Price On Square Footage?

Measuring square footage helps painters estimate the amount of paint and other materials required, plus the time involved in the project. Using the typical square footage formula (length x width), you only get an accurate estimate of the floor space, but painters typically need the square footage of the walls.

Instead, painters typically measure the square footage of walls by taking a measurement of the height of the room, excluding baseboards, and multiplying it by the length of walls, excluding windows and walls, to create this formula: 

Height x Length

Most painters charge based on square footage, with an average cost of $1.50 – $3.501 per square foot for interior spaces.

Why Is Square Footage Important For Flooring Installation?

Accurately calculating square footage allows you to budget for flooring costs. It’s a good idea to buy 10% – 20% more flooring than the square footage to cover any calculation mistakes.

How Much Does Square Footage Affect Appraisal?

More square footage in an appraisal will increase the likelihood of a property selling for the amount specified in the contract. This is why sellers want to list as much square footage as possible so they can earn their original listing price. Buyers also desire higher square footage since they’ll receive a larger home than anticipated.

The calculation of a home’s square footage in a tax assessment can sometimes differ from an appraiser’s square footage calculation if the appraiser uses an estimation method or if an error of communication occurs. Nonetheless, it’s not uncommon to see discrepancies between your square footage calculation and an appraiser’s square footage calculation.

Depending on the type of home, professional appraisal costs can range anywhere from $300 to $1,500.2 Single-family homes end up on the lower end of the spectrum, costing around $350, while multi-family homes can cost anywhere between $600 and $1,500.

Need extra cash for home improvement?

Use your home equity for a cash-out refinance.

NMLS #3030

The Bottom Line

Now that you’ve learned how to calculate the square footage of a house by hand and through our calculator, you’re set to break out the measuring tape. Whether you plan to install new flooring or need to know how much your home is worth, you’re one step closer to finding your dream home.

Miranda Crace

The Rocket Homes blog is here to bring you all you need to know about buying, selling and making the most of your home. Whether you’re thinking about becoming a homeowner, selling your current home or looking to keep your place in tip-top shape, our writers and freelancers bring their experience and expertise to meet you right where you are.