Redfin Estimate vs Zillow Zestimate, why online home values can miss the mark

If you have ever pulled up your home on Zillow and Redfin and thought, “Wait, that cannot be right,” you are not alone. I get calls about this every week. A homeowner sees one site suggesting a value that feels sky high, another showing something noticeably lower, and both are presented with enough confidence to make anyone wonder if they are missing something. The truth is simpler and a little messier: these numbers are not appraisals, they are algorithmic guesses. Sometimes they are close. Sometimes they are wildly off. And knowing why helps you use them the right way.

Let’s unpack what is going on behind the curtain, and how you should interpret these tools if you are planning to sell, buy, refinance, or just keep tabs on your equity.

[What Zillow and Redfin are actually doing]

Both Zillow and Redfin use automated valuation models, often called AVMs. An AVM is a computer model that predicts a home’s market value by comparing it to other homes and by reading as much data as it can find. That includes public tax records, recent sales, listing history, neighborhood trends, and home features like size, bed and bath count, and lot dimensions. Zillow also allows owners and agents to submit updates, which can help the model but can also introduce errors if the data is incomplete or inaccurate.

Redfin’s model pulls from similar sources, but it also emphasizes active listing data and sales data in markets where it has strong MLS feeds. When a home is listed, Redfin’s estimate typically updates quickly as new listing details hit the MLS. Redfin publishes that its estimate performs best on listed homes and gets less reliable when a property is not actively for sale.

So in plain English, both sites are trying to answer the same question with a similar mathematical approach. They are just working with slightly different inputs, and the inputs matter.

[Why the values can be unrealistic]

Here are the biggest reasons I see estimates drift away from real market value.

First, missing or outdated property details. Public records can lag behind reality. If you finished a basement, remodeled a kitchen, added a bathroom, or replaced a roof, the county record may not reflect it yet. Zillow or Redfin might not know those upgrades exist, or they might assume they do based on nearby homes. Either way, the model is guessing.

Second, the model cannot see condition. Algorithms do not walk through homes. They do not smell pet odor, notice cheap flip finishes, or appreciate a spotless lovingly maintained interior. Two homes can look identical on paper and feel completely different in person. Condition is often the difference between a strong offer and a lowball, but an AVM cannot measure it.

Third, your home may be unique compared to the neighborhood. Corner lots, extra large yards, backing to woods, a view, an unusual floor plan, or a premium school boundary can change value a lot. AVMs struggle when there are not enough truly comparable sales nearby. Zillow openly notes that accuracy depends heavily on local data quality and comparables.

Fourth, fast moving or uneven markets. In places like the Washington DC metro area, Northern Virginia, and Fairfax County, pricing can shift quickly based on interest rates, inventory, and buyer demand. Algorithms update on a schedule, and even a short lag can create a noticeable mismatch when the market turns.

Fifth, list price gravity. When a home is actively listed, AVMs often drift toward the list price, because that is one of the freshest signals in the data. If a listing is overpriced, the estimate can float upward. If a seller prices aggressively to spark competition, the estimate may temporarily read low. A model cannot tell strategy from reality.

[Which one is “better”]

Homeowners ask me this all the time, and I will give you a realistic answer. Neither platform is universally better. Their accuracy varies by region, and even by neighborhood. Redfin tends to track listed homes a bit more tightly in markets where MLS data is rich. Zillow tends to have broader nationwide coverage and a longer history of user submitted updates. Both admit that estimates are meaningfully less accurate for off market homes.

The more important point is this: even a small average error can be a large dollar swing for an individual homeowner. That is why relying on a single online estimate to set your price or your budget is risky.

[How to use these estimates the smart way]

Think of Redfin and Zillow as conversation starters, not decision makers.

They are helpful for spotting broad trends. If both sites are moving upward over time, that is a reasonable signal that your neighborhood is gaining value. If they both soften, that can be an early warning of a cooling market.

They are also useful for rough planning. If you are thinking about selling next season, it is fine to glance at these tools to get a ballpark sense of your equity.

But they are not reliable for pricing a home for sale, disputing an appraisal, or judging whether you overpaid for a property. Those situations demand a human level analysis of comparable sales, condition, micro location, and buyer behavior in your specific area.

[What a real market value check looks like]

When I prepare a pricing opinion for a seller, I am doing something no AVM can do. I am selecting true comparables, adjusting for differences that matter locally, and accounting for how buyers are behaving right now. I also walk the property to evaluate condition and features that never show up in tax records. That is why a strong comparative market analysis often lands in a different place than an online estimate.

If you want to know what your home would likely sell for today, the best next step is a local CMA paired with a walkthrough. You get a realistic range, backed by actual sales and actual buyer reactions, not a formula that is blind to your home’s story.

<<Andy Kim's Thoughts>>

Zillow and Redfin are powerful tools, but they are still tools. They work off data, and data is never perfect. In some neighborhoods they are impressively close. In others they are off enough to create false confidence or unnecessary anxiety.

If you are curious about your home value, use these sites to get oriented. Then talk to a local real estate professional before you make a real financial move. A number on a screen is fast. A real valuation is careful. And when money and timing matter, careful wins.

If you would like a realistic home value range for your property in the DC metro area, I am happy to help you sort through the comps and the context so you can make sure the number you are looking at matches the market you are living in.