Why Do Home Valuation Websites Differ So Much?
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Richard Haddad Executive EditorClose
Richard Haddad Executive EditorRichard Haddad is the executive editor of HomeLight.com. He works with an experienced content team that oversees the company’s blog featuring in-depth articles about the home buying and selling process, homeownership news, home care and design tips, and related real estate trends. Previously, he served as an editor and content producer for World Company, Gannett, and Western News & Info, where he also served as news director and director of internet operations.
On average, home values have increased at a rate of about 5% each year over the past decade and as much as 8% annually in the past five years. Curious about your own home, you may have tried online estimators and found yourself asking, “Why do home valuation websites differ so much?”
The accuracy of online home valuation sites can vary — sometimes by tens of thousands of dollars or more (see our test set below). This can be confusing when you’re trying to set realistic expectations for your home sale or financial planning.
So why do these sites differ so much? We’ll show you how free home value estimate tools work, and when and how they are best used.
Start With a Free Home Value Estimate
Enter a few details about your home, and we’ll provide you with a preliminary estimate of value in less than two minutes. This won’t replace a home appraisal, but it can be a helpful starting point.
Online home value estimates can vary — here’s why
Different property valuation websites use different data sources and algorithms, which can lead to big swings in estimated values.
“Valuation websites typically base their [estimates] on public and user-submitted data taken from multiple listing services (MLS), county and tax assessor records, and real estate brokerages,” explains Nick Stoddard, an expert property appraiser based in Kansas City.
Here are a few key reasons why home valuation websites can differ so much:
- Data availability: Some sites pull from public records, others rely on MLS data, and some use both and calculate an average. If your local records are outdated or incomplete, your estimate may be off.
- Errors in the system: Most of the sources that AVMs use are populated with data input by humans. Typos happen, including errors on construction dates, home sizes, purchase prices, and tax assessment amounts.
- Lack of comparables: If you own a unique, isolated, or custom-built home, an online valuation site may not be able to locate suitable nearby comparable properties.
- Update frequency: Home values can change quickly, especially when market winds blow from different directions. Some sites update their data more often than others, which can affect accuracy.
- Valuation models: Each website uses its own formula (or “automated valuation model”) to calculate your home’s value. These models weigh things like square footage, nearby sales, and zip code trends differently.
- Local market nuances: Online tools may not fully account for what’s actually happening on the ground, such as buyer demand in your neighborhood or events that impact local property values, such as a major employer opening up or closing down.
Examples: 8 valuation sites using the same home
To illustrate just how home valuation websites can differ, we tested eight online tools using this same house in the Atlanta area:
- Home size: 2,305 square feet
- Bedrooms: 3
- Bathrooms: 2.5
- Lot size: 0.3-acre
- Location: Dunwoody, Georgia (a suburb of Atlanta)
Here are the results, which we’ve rounded for easy comparisons:
| Online home valuation tool | Estimated value result |
| HomeLight’s Home Value Estimator | $507,800 |
| Zillow Zestimate | $467,400 |
| Redfin Home Value Estimator | $456,500 |
| Realtor.com RealValue Tool | $488,600 |
| RE/MAX Home Value Estimator | $590,900 |
| Bank of America Home Value Estimator | $495,800 |
| Chase Home Value Estimator | $453,300 |
| Eppraisal Home Estimate Tool | $655,200 |
As you can see, the estimated values range from a low of $453,300 to a high of $655,200, a difference of more than $200,000. For a better perspective, the median price estimate from all the sites calculates to $492,200.
This variance demonstrates how home valuation websites can differ and why these tools should be considered a preliminary or ballpark estimate — and not a substitute for a professional home appraisal.
Stoddard points out that online valuation websites rely heavily on surface-level data. “Like square footage, number of rooms, and the value of similar (nearby) homes.”
This can be a good starting point, but Stoddard cautions that the algorithms are not able to tell the whole story. “Let’s say you upgrade your basement or replace the carpet with hardwood flooring; home valuation sites don’t factor in those upgrades.”
What sellers should know about online home values
Online estimates can be helpful when you’re just starting your research, but they’re not meant to replace professional opinion. As Stoddard noted, these tools can’t see things like your kitchen remodel, your new roof, or how well you’ve maintained your property.
In addition, many home valuation sites have struggled with fast-changing local markets in recent years. That’s why relying solely on an online estimate could cause you to overprice or underprice your home, which can impact your final proceeds.
It’s best to think of these numbers as a rough estimate. If you’re getting ready to list, Stoddard recommends finding a local expert who will visit your home in person and compare timely, hyper-local data.
How to get a more accurate home value estimate
If you’re serious about selling, you’ll want more than just a rough estimate. Here are a few ways to get a much clearer picture of what your home is actually worth:
- Comparative market analysis (CMA): A top real estate agent can provide a CMA that looks at recent sales of similar homes in your area. This gives you a local, real-time snapshot that’s far more precise than an algorithm.
- Pre-listing appraisal: In some cases, sellers choose to pay for a professional pre-listing appraisal. While not always necessary, it can add a solid layer of confidence to your pricing — especially in unique or high-value markets.
- Local agent insight: A good agent knows what buyers are looking for right now. They can evaluate your home’s condition, upgrades, unique features, and overall appeal in ways an online tool never could.
Pricing your home for sale: Strategy matters
Setting the right price isn’t just about what your home could be worth — it’s also about how it compares to other listings and what the current market will support.
Overpricing can lead to fewer showings, longer days on market, and eventual price drops. Underpricing might generate fast interest but leave money on the table. The right pricing strategy strikes a balance between attracting serious buyers and making the most of your proceeds.
A skilled agent will help you weigh local comps, buyer demand, seasonal timing, and your own selling goals to land on a price that makes sense for your situation — not just what a website algorithm suggests.
Find a Top Agent to Sell Your Home for More
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Boost your sale proceeds with smart preparations
Top agents will tell you that the three Ps for the most profit in a home sale are Price, Presentation, and Promotion. The supporting P word in this advice is Preparation. The condition of your home and its curb appeal will heavily influence the final sale price.
A seasoned real estate agent can help you decide what to fix and what not to fix. They can tell you whether staging will help, and how to position your home to stand out in your specific market. Even minor improvements to your home, like fresh paint or landscaping touch-ups, can create a stronger first impression and lead to better offers.
Working with the right agent gives you access to professional marketing, negotiation experience, and a network of interested buyers. HomeLight data shows that the top 5% of agents sell homes for up to 10% more than average agents. The best preparation starts with finding the best agent.
Final thoughts on home valuation websites
Home valuation websites can give you a quick sense of your home’s potential worth, but they’re far from the full picture. Each site uses different data and methods, which is why estimates often differ so much.
If you’re thinking about selling, don’t rely on an online estimate alone. Talk to a local real estate agent who can offer personalized insights, guide your pricing strategy, and help you prepare your home for a successful sale. When you combine online research with expert advice, you’ll be in a stronger position to sell with confidence — and walk away with more in your pocket.
To get started, use Homelight’s free Agent Match platform. We analyze over 27 million transactions and thousands of reviews to determine which agent is best for you based on your needs. Agents can’t pay us to be featured, so you know you’re talking to a performance-proven expert.
Editor’s note: Many agents will provide a free CMA home value estimate when you reach out for a consultation.
Header Image Source: (iriana88w/ Depositphotos)
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