How to Measure Your Home’s Square Footage and Estimate Its Value

Something as concrete as the square footage of your home doesn’t seem like it could be up for interpretation. It’s math, after all. There should be one correct answer, right?

Not necessarily. Calculating the square footage of a home is variable and complicated and there’s more than one way to do it. This can be unsettling when it comes to what is likely the largest investment you have.

But don’t worry! To help us understand how to know what counts toward the square footage of your home and how it affects your home’s value, we’ve done some research and called on two experts.

We spoke with Angelina Keck, a top-selling Texas real estate agent who ranks in the top 1% of agents in Houston; and Richard Henley, a Conway, Arkansas agent who works with 71% more single-family homes than the average agent in the area. They shared their insights and tips for calculating square footage and why it matters to the value of your home.

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What counts toward the square footage of a home?

The official square footage of a home includes finished spaces that are heated and cooled. This is called the gross living area, or GLA. Generally speaking, to be considered part of the GLA, the area must be livable all year, have walls and finished floors, be heated and cooled, and have a ceiling that is at least seven feet high, though there are other specifics that can affect whether or not a space counts towards the GLA.

Why is the accurate square footage of a home so important?

A home’s value is predicated on a number of factors, and while square footage is just one of them, it’s an important one.

“The value of your home is directly tied to the square footage,” says Henley. “During the sale process, the appraiser will measure your house. If you have marketed the home with the incorrect square footage, that can come back to get you when the appraisal comes in.”

Consider what would happen if the appraisal comes in and reveals the home is smaller than what you were marketing it as. In this case, the appraised value may come in lower than the sales price, creating an appraisal gap and putting the buyer’s mortgage approval in jeopardy, and you may have to lower the price to account for the lower square footage.

In contrast, “If you’ve been marketing in the house smaller than the appraiser finds, then you’ve cost yourself money,” says Henley. “The sales price could have been higher.” Incorrect square footage can also affect the time it takes to sell the property.

Henley shared a story wherein a seller’s home had been sitting on the market for quite a while. The homeowner reached out to Henley for help. When Henley showed up and measured the house, he found that it was 400 square feet less than what was listed because the seller had included an area that didn’t count toward the GLA. Once the square footage was adjusted and the price lowered, the property sold in a week.

Who should measure the square footage of my house?

As of April 2022, Fannie Mae, a government-sponsored enterprise (GSE) that buys mortgages from lenders, requires that appraisers follow the Square Footage Method for Calculating: ANSI® Z765-2021. While this standard can’t be followed when measuring apartment-style condos, Fannie Mae requires it for any non-apartment-style residence. This includes townhouses, rowhouses, and single-family homes.

Because Fannie Mae purchases about half of all mortgages that lenders make, the criteria that lenders have for their loans typically conform to Fannie Mae standards, which now include having an appraiser measure a home’s square footage, compliance with the ANSI standard, and a computer-generated rather than a hand-drawn sketch.

Keck also recommends hiring an appraiser to measure the square footage. It’ll cost you about $300 to $400, and “they’ll put their stamp on it so it’s official. This is the best and most reliable way to estimate square footage.”

How do I measure the square footage of my home?

If you’re not ready to hire an appraiser but still want a good idea of the size of your house or want to double-check the appraiser’s measurements, you can measure the home yourself by following these steps.

Gather your tools

First, you’ll need a measuring tape or a laser distance measurer. Chances are, you have a measuring tape on hand, and you can definitely use it, but a laser level has the advantage of providing a real-time measurement in a handheld device. With a measuring tape, you may also need a buddy to help you pull it across the room and hold it steady while a laser allows you to do everything on your own. Bob Vila recommends this one as the best overall and this one as the best bang for your buck.

You’ll also need:

• A sketchbook or piece of paper
• A writing utensil
• A calculator

Check out measuring technology

You can download measuring apps like Ruler App or Distance Meter, but you’ll be fighting pop-up in-app ads while you try to measure. We downloaded quite a few to test them out, and we’d rather stick with a measuring tape or laser distance measurer.

You can also use websites like Calculator Soup®, The Calculator Site, or Calculator.net. Some square footage calculator sites also have a built-in price-per-square-foot calculator to help you estimate the value of your home.

Get out the sketchbook

If you’re measuring for yourself and not to comply with ANSI standards, you can just do a rough sketch of the exterior of the home or each room, including closets and pantries, and write down measurements as you go.

When you’re sketching irregular-shaped rooms, break it down into as many rectangles as possible to help the calculations go more smoothly.

Measure, measure, measure

Square footage should be measured from the exterior of the building initially. After exterior measurements are taken, it’s time to take a closer look at the interior and make adjustments for things like stairs which count towards square footage, and the dead space below them that doesn’t.

If you want to know the square footage of each room individually, then go room by room measuring and labeling your sketch as you go.

Do some math

This may feel like a trip back to high school geometry class, and it kind of is. While you can definitely use a square footage calculator, it doesn’t hurt to know how square footage is calculated for different shapes, such as a square, rectangle, or circle.

Here’s an example showing how to calculate the area of a room:

Below is an example of a house with each room measured individually — we’ll assume they’re all average-sized square or rectangular rooms.

If you measure each room and add them together, it’s important to remember that an official square footage measurement will be taken from the outside and include the area found in the exterior walls.

Example measurements shown in feet

How does square footage affect the value of my home?

This is a tricky question. The size of a home is very important to determine its value, but that’s not the only factor. A 1,200-square-foot home that is updated and move-in ready might be more expensive than a 1,500-square-foot home that needs extensive work.

Listings typically have the price per square foot listed, so a lower price per square foot will give you a good idea of what kind of “deal” you may be getting while a higher price per square foot can indicate added features (like a pool or updated cabinets) that can’t be calculated in the actual square footage measurement.

Other spaces that aren’t counted in the GLA but could add value to your home include:

• Unfinished basement
• Attic
• Garage
• Detached guest house — also known as an Accessory Dwelling Unit (ADU) or mother-in-law-suite
• Pool house
• Rooms with sloping ceilings
• Storage areas not attached to the house or unfinished storage areas inside the house

The home’s amenities and certain upgrades will also affect the home’s value and be reflected in the price per square foot even though they aren’t part of the square footage. Some examples include:

• An updated kitchen
• Updated bathrooms
• A pool
• Outdoor space (fenced in yard, patio, outdoor kitchen, etc)
• Hardwood floors
• A new roof
• New garage door

Another factor in how square footage affects the value of a home is where the square footage is located. For instance, the square footage found in an enclosed, heated and cooled porch area may have a higher value than below-grade square footage that is worth less.

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Expert tips about your home’s square footage

What is the biggest misconception sellers have about a home’s square footage?

Henley emphasizes that square footage is just one of the many factors that go into pricing a home. “The four big factors of pricing a home are location, condition, marketing, and price. So I really try to get my sellers to recognize that square footage is important, but it’s no more important than how clean your house is or how nice the landscaping is,” he says. It’s just one of the many, many factors that go into pricing the home.”

Ultimately, he says, “It’s not as simple as calculating the square footage, multiplying by $150 and, boom, you’ve got the price.”

Another misconception, according to Henley, is that more is always better. He has seen instances where clients have converted their garage into a living space. They gain square footage in the form of more heated and cooled space, but they lose the garage. So while a garage doesn’t count toward the total square footage it will likely positively affect the value of a home.

Can I hire a professional to measure my home’s square footage

You can hire a professional to measure your home’s square footage and, in fact, you should. The buyer’s lender will likely order an appraisal through an appraisal management company (AMC) after their offer is accepted, and if the appraiser finds a discrepancy in your measurements and theirs, it can cause problems during the closing process. Having a professional measure the home prior to listing it can reduce the likelihood that problems will arise later.

Can I just use the square footage listed on my tax documents?

Henley cautions against using your tax documents to determine the square footage of your home, saying “The problem with tax records is they measure from the outside, but they don’t go inside to check for dead spaces, they don’t go into the garage to check to see if there’s a big garage storage room. So tax records are never really accurate.”

Are there other sources that might already have accurate home measurements for my home?

If your house has sold before, then it was probably measured by an appraiser the last time that it sold. This isn’t always the case as some cash buyers don’t order an appraisal. If it was measured, you can locate that report and use it as a jumping-off point, but you may still want to have an appraiser measure to ensure that the measurement is accurate and complies with ANSI standards.

If you live in a townhome, condo, or tract home, the original architectural drawings or plans may also show your home’s square footage.

Work with a top agent to determine your home’s value

Ultimately, using square footage to estimate the value of your home is an important factor, but there are lots of other factors that contribute. You can also use tools, like HomeLight’s free Home Value Estimator to give you a real-time ballpark estimate of your home’s value. Working with a top agent who can provide a comparative market analysis (CMA) will also help you determine how the square footage of your home affects the value.

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