How Do You Calculate the Square Footage of Your Home?

calculate square footageThe square footage of your home plays a large role in how to market your home and the buyers that will be attracted to your home as well.

In this article we will be discussing How Do You Calculate the Square Footage of Your Home?

Obviously, a 1200 square foot home will function much differently than a 4000 square foot home. 

The cost of construction alone will be quite significant.

It also is a large factor in determining the correct price for a home.  Calculating the square footage of a house accurately is important for many reasons. Thisyou should never value your home strictly by square footage.

Often, a real estate agent will turn to town records or a previous appraisal to determine the square footage of your home. 

Using the town’s listed square footage limits the agent and the seller’s liability.  As a listing agent, I like to verify the information myself as sometimes the town records can be off significantly.

Many home buyers are choosing the homes they look at based on a square foot range.  Often buyers will avoid homes below a certain square footage.  So of course home sellers want to show their home is as large as possible.

How Does An Appraiser Calculate Square Footage of Your Home?

We will take a look at how an appraiser will calculate the square footage of your home.  Most buyers will most likely secure a home mortgage to buy your home.

Because the bank has the ultimate say in the value we will look at how the bank’s appraiser appraises a home. And, more importantly, how they calculate the square footage of your home when they place a value on it.

We are going to talk about calculating the gross living area (GLA).  This is what Fannie Mae (FNMA) looks at when calculating the square footage of your home.  FNMA determines the guidelines used to sell mortgages on the secondary market. 

Most home mortgages are underwritten to FNMA guidelines and most loans are underwritten to FNMA’s guidelines.

Above Ground Space

Only space above grade or above ground can be used to calculate the square footage.  If you have finished basement space and it is completely underground or partially underground this cannot be used as above-ground space for the total above-ground square footage.

Finished, Livable Space

Only finished, livable space can be used in the calculation of square footage.  Obviously, while an attic is typically unfinished it is above ground but cannot be included because it is not finished in a similar fashion to the rest of the home. 

This requires that livable space is finished similarly to the rest of the home and in most cases (here in New England at least) heated in a similar manner to the rest of the house.

Contiguous Finished Space

For finished space to be considered in the square foot calculation of a home, it also must be contiguous to the other living space of a home.  Finished areas above detached garages, barns etc… or even areas above attached garages that have an unfinished area separating them cannot be used in the square foot calculation.

You may have a 3 season room or enclosed porch that may be finished but unless it is heated and/or cooled like the rest of the home that is not going to be included in the square footage of your home.

Don’t worry, even if you have a significantly finished basement or 3-season room, while it may not contribute to the square footage of your home, significant adjustments can be made for them to increase the value of your home.

Calculate square footage on your home accurately

So How Do You Calculate the Square Footage of Your Home?

As I said earlier in the article we are looking at the Gross Living Area.  So let’s take a look at how to calculate the gross living area of your home.

A simple two-story colonial is easy.  You take the outside dimensions and multiply it by two.  A 24 x36 colonial would have a GLA of 1,728 square feet.  Where it may start to get a little more difficult is when a home is more than just a basic rectangle or when the two floors are different sizes.

Take a cape home with 24×36 exterior dimensions.  Because a cape’s upstairs living space is not all usable you would not just double the calculation. 

FNMA guidelines state that the ceiling height needs to be 7 feet.  There will be eves that are unfinished that of course will not be counted.  But many capes will have finished space under the roof line that may not have a ceiling height of 7 feet for even the finished spaces.

In this case, a cape and a colonial with the same foundation size can have very different square footage due to the second floor.


Why Is It Important to Calculate Square Footage of Your Home Correctly?

The size or square footage of your home should not be treated cavalierly had it can affect you as the home seller in several ways.


If you overstate your home’s square footage and the buyer of your home later finds out it was overstated, this could open you up to a lawsuit after the sale of your home.  This can be cumbersome, time-consuming and costly.

A few feet of discrepancy won’t get you in trouble, but if you start to have a discrepancy of 5-10% or more you are certainly opening up yourself to liability.  So how do you avoid liability?  Use the following which are professionals who calculate the size of a home and are assumed to be correct:

  • Tax Record
  • Appraiser
  • Bulilder’s Plans

If you think there may be a discrepancy measure your home but do it accurately.

I also spoke with attorney Rick Carter out of Reading MA.  He pointed out that there will always be some discrepancies from one person measuring to another but they should be minimal. 

A gross misrepresentation or even fraudulent representation can certainly lead to a potential lawsuit down the line.


While not the end all be all of determining the value of your home, the size of your home plays a large role in determining the price of your home.  Overstate your square footage and your house will probably be overpriced compared to the competing homes. 

Understate your square footage and you could be leaving money on the table and not receiving top dollar for your home.

One last point is your home needs to appraise.  If you based your home on square footage that isn’t used by an appraiser you run the risk of tying your property up with a deal that may not close because your property does not appraise.

Not Showing Your Home To The Right Buyers

This section has to do with value but it needs to be said.  Overprice your home because you overstated your square footage, and again your house will not compete with similarly priced properties.

Buyers are more educated about the market than you think.  200 square feet on a 1800 square foot home could mean the difference between an office or even a small bedroom. 

If a buyer makes a decision to see your home based on the square footage, they could be disappointed when they arrive. 

With the prevalence of the internet in a buyer’s home search given that a buyer cuts off the upper price tier of the home search, the right buyers might not even know about your house if it is over their maximum price point.

Home Buyers and Square Footage

A home’s square footage is not the end all be all when you purchase a home.  The layout can make a smaller home feel large and a larger home feel small. 

For example, an open floor plan will feel larger, whereas a home with lots of hallways and walls will feel smaller.

With that said, when you are doing your due diligence on a home with your buyer’s agent it is a good idea to verify the square footage yourself.  You don’t want to buy a home thinking you are getting much more square footage than you are.  it is not unusual for a seller or listing agent to overstate square footage. 

A simple check is the tax assessor’s office.  Most towns have a simple sketch of the floor plan with dimensions.  You don’t need to be perfect down to the inch. 

But if a seller is stating the home is 2200 square feet you don’t want to move in to find out they included a finished basement in the home’s square footage.

Final Thoughts

As a home seller, it is important to calculate your home’s square footage for many reasons. 

Overstate the square footage and it could lead to trouble legally or prevent your house from being sold or require multiple price changes before it is eventually sold.

If your lucky maybe you find that the assessors office or an appraisal has left a significant amount of square footage on the table.  This certainly can increase the value and appeal of your home.

Work with your listing agent to get your homes square footage accurate.  If need be they should measure the house.  Ultimately though you are responsible for what your agent does on your behalf so always make sure you are on board with what your listing agent is doing.

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How Do You Calculate the Square Footage of Your Home? is provided by Kevin Vitali. If you would like to sell your home give me a call at 978-360-0422 and let’s get the process started.

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