When it comes to measuring square footage, the truth is that it depends on who’s doing the measuring. That might sound vague, but the process can vary quite a bit between appraisers—even though there’s an official standard in place.
Square footage plays a key role in real estate, especially during appraisals. Buyers and homeowners often assume it’s an exact science, but in reality, even professionals can come up with different results based on how they interpret or apply the guidelines.
The correct answer should be: the method for calculating the square footage of a home is determined by the American National Standard Institute (ANSI).
How Is Square Footage Measured
The ANSI standards are taught by the leading appraisal organizations. Many state licensing boards require these standards in an effort to promote uniformity and professionalism in calculating square footage. If you really want to “nerd out” you’re welcome to check out ANSI’s Square Footage Guide.
The Role of ANSI in Appraisals
Appraisers are guided by the American National Standards Institute (ANSI), which outlines how square footage should be calculated. These ANSI standards are designed to promote consistency across the appraisal industry and are often required by state licensing boards.
Appraisers who follow ANSI guidelines will:
- Measure from the exterior of the property
- Include only finished, above-grade living space
- Exclude garages, unfinished basements, and porches unless they are enclosed and finished
Even with these standards in place, not every appraiser takes the same approach. Some will conduct manual measurements while others rely on existing data from third-party sources.
Common Sources Appraisers Use
In Dallas and across Texas, appraisers may pull square footage information from a few different sources:
The Central Appraisal District (CAD): These records are used frequently for resale homes, but they’re not always up-to-date or accurate.
Builder blueprints: For newer homes, appraisers may reference original plans. These are typically reliable, but modifications made during construction or after move-in may not be reflected.
Prior appraisals: If the home has been appraised recently, some appraisers may use that report as a reference—without remeasuring the property themselves.
These shortcuts aren’t necessarily wrong, but they introduce a margin of error. Unless the appraiser is physically measuring the property themselves, there’s always a chance something was missed or misreported.
Why Price Per Square Foot Is Misleading
Many buyers and homeowners fixate on the price per square foot when looking at home values. But here’s the thing: price per square foot is a result, not a method. It’s simply a way to divide the appraised value by the size of the home.
Appraisers don’t start with a price per square foot and multiply it out. They look at a wide range of factors:
- Location and neighborhood
- Lot size and land value
- Condition and quality of finishes
- Room count and layoutComparable sales in the area
Square footage matters, but it’s not the only factor—and not the most important one in many cases. A well-maintained 2,500 sq. ft. home in a great Dallas neighborhood could appraise higher than a 3,000 sq. ft. home that needs updates or is poorly located.
The Art and Science of Measuring
Mark describes appraisal as 95% science, 5% art. The science is the measurement process and ANSI standards. The art is in the interpretation—those gray areas that allow for human judgment.
Take something like a stair landing. Some appraisers will include that space in the second-floor measurement, while others won’t. Or consider rounding: one appraiser might round to the nearest foot, while another uses the more precise 1/10th of a foot, as ANSI recommends.
Those differences might seem small, but they can affect the final square footage by dozens of square feet.
Real-Life Example: When Two Appraisers Disagree
Here’s a real-world example from one of our clients in Texas. Two appraisers were asked to measure the same home:
Lazy Linda
- Reported the home as 4,228 square feet
- Rounded all measurements to the nearest full foot
- Missed architectural details like the breakfast room extension
- Overstated square footage by failing to follow the floor plan accurately
Better Brenda
- Reported the home as 3,987 square feet
- Used precise measurements to the nearest 1/10th of a foot
- Included all protrusions shown in the architectural plan
- Omitted stair tread space in the second-floor count (about 100 sq. ft.)
Even though Brenda followed best practices, she still missed something. But her report was far more aligned with the property’s true dimensions than Linda’s.
This example shows how two professionals can arrive at significantly different numbers based on their technique, tools, and interpretation.
When Square Footage Makes a Big Difference
A few square feet one way or another won’t typically make or break a deal. But large discrepancies can.
Here’s when square footage can cause real issues:
- Additions not reflected in public records: If you added a room or finished a basement, the appraisal could come in low unless the new space is accurately measured and included.
- Incorrect county records: This is especially common in older Dallas homes where renovations may have happened decades ago.
- Condo and townhome misclassifications: Some appraisers miscalculate shared wall space or exclude usable interior areas.
If the appraised value comes in too low, it can impact your ability to finance the purchase, especially if you’re using a low-down-payment loan.
What to Watch For in Your Appraisal Report
Whether you’re buying, selling, or refinancing, it’s smart to review your appraisal report when you get it. Here are a few things to check:
- Does the square footage seem accurate based on your experience with the home?
- Are all living areas counted? (finished basements and converted garages may or may not be included)
- Are there any notes about where the square footage was sourced from?
- Do the floor plan sketches match the layout of your home?
If something seems off, you have the right to challenge the appraisal. At Mortgage Mark, we’ve helped many clients work through these issues and gather the right documentation to get their appraisal adjusted.
Working With a Knowledgeable Mortgage Team
The appraisal is just one piece of the loan process—but it’s an important one. Having a lender who understands how to navigate discrepancies, communicate with appraisers, and advocate on your behalf can make a big difference.
At Mortgage Mark, we work with homeowners across Dallas, the surrounding metroplex, and throughout Texas to make sure every piece of the process—from preapproval to closing—is as smooth and accurate as possible.
If you’re concerned about your appraisal or need guidance on what to expect, we’re here to help.
What’s Next
Mark and the team can walk you through the entire home loan process and mortgage loan process. Call us with any questions and let us know how we can help.
Next: processing & credit approval
Previous: home appraisal process
Mark Pfeiffer
Regional Sales Manager
Loan Officer, NMLS # 729612
(972) 829-8639
MortgageMark@MortgageMark.com