Five Reasons Why Asking Zillow What Your House is Worth is a Bad Idea

Let me start with this: Zillow is a household name. I respect the reach they have and the tech they’ve built. But when it comes to understanding what your house is really worth—not just as a number on a screen, but in the real-world context of timing, condition, and strategy—Zillow can be dangerously misleading. As a full-time real estate professional working here in the heart of Silicon Valley, I’ve seen it all. I’ve sat across the kitchen table from countless homeowners who were either thrilled or dismayed by what Zillow told them…only to find out the truth was something else entirely.

In this article, I want to break down the five big reasons why relying on Zillow for your home valuation could actually hurt you—whether you’re thinking of selling, refinancing, or just trying to get your financial bearings.

1. Zillow Doesn’t Know Your Home

Zillow has never been inside your house. It hasn’t walked through your highly functional and sought-after floor plan, smelled the lavender blooming in your backyard, or felt the difference the amazing quality and quantity of natural light your home enjoys. These automated valuation models (algorithms) are amazing at processing data—but they can’t process nuance. They don’t see the upgrades, the deferred maintenance, or the architectural charm that makes your home more (or less) desirable than your neighbor’s.

In the real world, buyers aren’t comparing your home to an average of past sales. They’re walking through it. They’re falling in love with the light in the family room, the layout of the kitchen, or the peace of the backyard. Zillow can’t capture that.

2. The Zestimate is Based on Incomplete and Delayed Data

While nobody outside of Zillow knows the exact formula used by the fabled Zestimate, it’s reasonable to assume it is largely calculated using public records and MLS data. But public records can lag by months, and even when MLS data is available, it doesn’t always reflect off-market transactions, concessions, or specific sale conditions that affect value. And in markets like Silicon Valley, where micro-markets shift block by block and month by month, that time lag can distort reality.

If you’re relying on the Zestimate in a fast-moving market, you might base major financial decisions on outdated information.  I’ve also seen people hold off listing their home for months, waiting for the Zestimate to catch up to reality. Spoiler: it doesn’t always catch up, and in fact, it could be totally overstating how much your home is worth even today. Waiting for the Zestimate to increase before putting your home on the market, or negotiating an offer around the Zestimate value, is like picking stocks based on the answers you get from the Magic 8 Ball.

3. It Ignores Market Psychology and Buyer Behavior

There’s a human side to pricing—and Zillow doesn’t understand human behavior. For example, buyers react to numbers emotionally. A home listed at $1,998,000 may draw a completely different crowd than one priced at $2,050,000. Strategic pricing is about understanding how buyers think, not just plugging numbers into an algorithm.

Also, the way your home is marketed can affect what it sells for. A beautifully presented home with smart, well-executed photography and compelling marketing copy will fetch a different price than a cluttered, dimly-lit home with grainy cell phone pictures—even if they’re otherwise identical. Zillow doesn’t begin to account for this.

4. It Can Undermine Your Negotiating Position

Here’s a real story: I had a seller whose home had a Zestimate $200,000 lower than what we believed the property could command. We listed it at our advised price—and got multiple offers above asking. One buyer submitted a lower offer and cited the Zestimate as justification.

See the problem? A bad Zestimate can give buyers ammunition to lowball you—even when the market is in your favor. And while an experienced agent can help you counter that, it’s a battle that you must be prepared to fight.

5. It Gives a False Sense of Precision

Zillow presents the Zestimate like it’s a precise number, often to the nearest dollar. That’s misleading. Home value is inherently fluid. It depends on who your likely buyer is, what else is on the market, how your home shows, and what kind of competition you face. The same home could sell for a different price next week depending on who walks in the door.

Zillow itself acknowledges that their Zestimates are often off by tens of thousands of dollars. In some markets, the median error rate is more than 6%. In Silicon Valley, that could mean a “mistake” of $150,000 or more. That’s not a margin of error—that’s a game-changer.

Your Neighbor Sold their House too Cheap!

Alternatives to Zillow’s Zestimate

Zillow’s Zestimate has long been the dominant home valuation estimate online. It’s widely used and updated regularly, but it’s not the only tool available—and certainly not without its flaws. If you’re looking for alternatives, Redfin.com, Realtor.com, and ComeHome.com all offer compelling AVMs (automated valuation models) with unique strengths.

Here’s a comparison of how each of these alternatives stacks up against Zillow’s Zestimate.

Redfin Estimate vs. Zillow Zestimate

Strengths Compared to Zillow:

• MLS Data Integration: Redfin’s AVM is built primarily on direct access to Multiple Listing Service (MLS) data, which can lead to more accurate and timely estimates in markets where Redfin operates. In contrast, Zillow often relies on public records, which may be outdated or incomplete.
• Model Transparency: Redfin shows confidence scores and ranges around their estimate, helping users gauge uncertainty. Zillow, while advanced, doesn’t provide this same level of transparency for individual properties.
• Timeliness: Redfin’s estimates are updated daily, which may lead to quicker adjustments for recent sales or listing changes than Zillow in some cases.

Weaknesses Compared to Zillow:

• Limited Market Coverage: Redfin’s estimate is only available in markets where it has sufficient data coverage, mostly urban and suburban areas. Zillow, by contrast, covers nearly the entire U.S., including rural areas.
• Fewer Off-Market Estimates: Zillow provides Zestimate figures for most off-market homes, while Redfin tends to prioritize active or recently listed homes.

Bottom Line: Redfin may offer more accurate valuations in select markets due to its MLS access and transparent model, but Zillow is more comprehensive in coverage and reach.

Realtor.com (Multi-Estimate Model) vs. Zillow Zestimate

Strengths Compared to Zillow:

• Multiple Estimates, One View: Realtor.com does not calculate its own AVM but aggregates estimates from third-party providers such as CoreLogic, Quantarium, and Collateral Analytics. This gives users a comparative view of how different models interpret the same property.
• Less Biased Presentation: Unlike Zillow, which presents a single authoritative number, Realtor.com encourages users to consider a range of values, helping to prevent overreliance on a single estimate.
• Strong Data Sources: The AVMs presented on Realtor.com often pull from institutional-grade data used by mortgage lenders and appraisers.

Weaknesses Compared to Zillow:

• No Unifying Estimate: Realtor.com leaves interpretation up to the user; it does not average or reconcile the different AVMs into a single number, which can be confusing for those seeking a clear answer.
• Interface Complexity: For users unfamiliar with real estate valuation, seeing three different estimates may raise more questions than it answers.

Bottom Line: Realtor.com’s home valuation offers a more nuanced, multi-model view than Zillow, which can be an asset for informed users. However, it lacks the simplicity and consumer-friendliness that make Zillow popular.

ComeHome.com vs. Zillow Zestimate

Strengths Compared to Zillow:

• Institutional-Grade Model: ComeHome is powered by HouseCanary, which provides valuation models used by banks, mortgage servicers, and institutional investors. This can make its estimates more rigorous and suitable for financial decision-making.
• Holistic Property Insights: ComeHome doesn’t stop at home value—it also provides data on rental potential, market trends, and ROI projections for improvements, which Zillow typically doesn’t include at the same depth.
• Updated with Recent Sales: Like Zillow, ComeHome incorporates recent transaction data, but with an emphasis on data quality rather than quantity.

Weaknesses Compared to Zillow:

• Less Brand Recognition: Zillow’s Zestimate is more widely known and accepted among consumers and agents alike.
• User Accessibility: Some features on ComeHome require registration or are embedded within partner bank and lender platforms, while Zillow is fully open to all users.

Bottom Line: ComeHome offers a more advanced and professional-grade valuation experience compared to Zillow, but its accessibility and name recognition are weaker, especially for casual users.

Each AVM provides a different lens on property valuation:

• Zillow is convenient, widely recognized, and offers nationwide estimates, but it can be opaque and inconsistent in accuracy.
• Redfin provides more transparent and possibly more accurate estimates in areas where it has strong data coverage.
• Realtor.com emphasizes the variability in AVMs by showing multiple estimates side-by-side, giving a broader context.
• ComeHome delivers lender-quality analytics, appealing more to data-driven users and professionals.
• Homes.com offers user-friendly interfaces and strong neighborhood context, but its property value estimates are less transparent and generally less robust than those from Zillow or Redfin.

For anyone serious about understanding a home’s value—whether buying, selling, or investing—it’s best to consult multiple tools if you’re looking into what your home could be worth. Comparing estimates from these platforms can reveal discrepancies and help validate assumptions, especially when combined with insights from a local real estate professional.

Homes.com AVM vs. Zillow Zestimate

Strengths Compared to Zillow:

• Integration with Homesnap and MLS Feeds: Homes.com is now part of the CoStar Group and draws from its Homesnap technology and MLS partnerships, potentially yielding high-fidelity data in many metro markets.
• Tightly Tied to Agent Networks: Homes.com positions itself as “agent-first,” which may lead to AVMs that better reflect on-the-ground market conditions.
• Simplified User Experience: Presents the home value alongside helpful visuals, comps, and neighborhood data in a user-friendly format.

Weaknesses Compared to Zillow:

• Limited AVM Transparency: Homes.com doesn’t always detail how their valuation is calculated or how frequently it’s updated.
• Smaller Market Share: As a newer player in consumer-facing AVMs, Homes.com lacks the widespread adoption and awareness Zillow enjoys.
• Less National Coverage: May not provide estimates in less active or rural areas.

Bottom Line: Homes.com’s valuation tool offers a fresh approach to property values, blending MLS-informed estimates with a clean interface and strong agent connectivity. However, Zillow still holds an edge in scale, visibility, and update frequency across broader geographies.

Everyone wants to know…

Automated Valuation Models Are Ballpark Values At Best

Automated Valuation Models (AVMs) are designed to offer quick, data-driven estimates, but their usefulness has clear limits. They rely heavily on historical and publicly available data, which means they often miss nuances like recent interior renovations, unique architectural features, or local market shifts that haven’t yet shown up in the numbers. As a result, even the most advanced AVMs can produce estimates that are significantly off-base. These tools are helpful for setting general expectations, but anyone making serious decisions—like pricing a listing or preparing an offer—should treat AVMs as a starting point, not a definitive answer.

For example, I ran my own house through these systems, and here’s what I got:

• Zillow: $1,506,200
• Redfin: $1,466,113
• ComeHome: $1,657,289
• Realtor.com: $1,646,100
• Homes.com: $1,751,938

There is a spread of nearly $300,000 between the lowest estimate (Redfin) and the highest (homes.com).  Zillow is the 2nd lowest value, so should I toss that out along with what I got from Redfin?  Of course, I prefer the value I got from homes.com because it gives the highest number, but really, which should I trust?  Who is most credible?  Just how exactly did they come up with those numbers?  Should I average them together and get a reliable figure?  How would any of these values inform my decision to sell my home, what list price I should choose, what work I might need to do to my home to get the suggested price, or what offer I should accept?

Looking at all of these, I’m left with more questions than answers.

What Should You Do Instead?

It’s fun to play around with these tools, but if you’re seriously considering a sale, I suggest you start with a professional home equity consultation. That’s what I offer. It’s not just about finding out what your home is “worth” in some abstract sense. It’s about calculating how much of your equity you could actually walk away with if you sold—after all the taxes, commissions, repairs, and other costs are accounted for.

We’ll also talk about strategy. Should you sell now, or wait? Should you paint the kitchen? Replace the roof? Rent it out? Convert the garage to an ADU? All these choices impact your bottom line—and no algorithm can give you that kind of advice.

It’s also about goals. Are you thinking about retiring? Downsizing? Helping your kids buy a home? Your strategy should reflect your life, not just the current market trends. When we sit down for a consultation, I want to understand your bigger picture, not just your property address.

You deserve a real conversation—not a robot’s guess. Let’s talk.

Final Thoughts

Look, I get the appeal of Zillow. It’s fast. It’s easy. It feels like it gives you control. But when it comes to your most valuable asset, you owe it to yourself to dig deeper.

Your home is more than just a box with square footage and a roof. It’s a financial vehicle, yes—but it’s also your history, your future, and for many of us, our legacy. Don’t let an algorithm define its value.

I’m here to help you get the real story—one that starts with understanding, not just estimating. Let’s find out what your home is truly worth – not just to you, but what it could be worth to someone else.

Downsizing Done Right

Silicon Valley Luxury Homes for Sale