How much can you trust a Zestimate?

Editor’s note: This article first appeared in Money Matters, a newsletter from Britannica Money, on August 2, 2026.

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It’s an estimate, not a sure thing.

© Jakub Krechowicz, New Africa, Who is Danny/stock.adobe.com; Photo illustration Encyclopædia Britannica, Inc.

If you’ve ever looked up a home on Zillow, your eyes were probably drawn to its Zestimate, a snapshot of what a home might be worth. A Zestimate can look oddly precise—for example, $428,213—making it easy to assume that it’s accurate.

If you’re a homeowner, you may have been surprised by just how much your home’s value has increased in recent years. Zillow’s estimate may reinforce that impression, but the number may not be as exact as it looks.

A Zestimate isn’t an appraisal or a professional opinion. It’s Zillow’s estimate of what a home might sell for today, generated by a computer model rather than a person. The company says the estimate is based on millions of pieces of data, including public records, recent sales, tax assessments, information from active listings, and details that homeowners provide.

Like any estimate, though, it’s only as good as the information behind it. If records are incomplete, outdated, or simply wrong, the Zestimate can be affected. Zillow acknowledges these limitations in its regulatory filings, noting that poor data quality and revisions to its valuation models can produce unexpected results.

The estimates also tend to be more accurate for homes that are actively listed for sale than for those that aren’t. That’s because a newly listed home brings with it fresh information, including the asking price, updated property details, photos, and other listing data that Zillow’s model can incorporate quickly.

Off-market homes often come with less reliable information. Recent sales may not exist, and basic property information may be incomplete, outdated, or incorrect.

That’s why a Zestimate is best viewed as a starting point, not the final word on what a home is worth.

A Zestimate draws on public records, listing data, tax information, homeowner updates, and other sources. The model can only evaluate the information it has. Poor data quality can affect the estimates it produces. Junk in, junk out, as the saying goes.

When the information behind a Zestimate is incomplete or incorrect, homeowners sometimes dispute the result, a possibility Zillow has disclosed in its filings.

I’ve seen firsthand how data issues can play out after noticing Zillow had two separate listings for my home, one of them with the wrong ZIP code. I reported the problem and was later told the listings had been merged (though both continue to appear).

When I asked Zillow about the issue while reporting this article, the company said one possible explanation is that it may still be receiving county parcel data that supports more than one property record for the same address.

Whether or not the duplicate listing affected my Zestimate isn’t the point. The episode illustrates a simple reality: An automated estimate is only as reliable as the information behind it.

A Zestimate can be a helpful reference, but it shouldn’t be the only factor when you’re making decisions that depend on your home’s value.

My own experience with Zillow’s Zestimate showed me just how important complete, high-quality data are to producing a reliable estimate. But even the best estimate isn’t the final answer. Ultimately, your home is worth what a buyer is willing to pay for it.