How Accurate is Zillow Home Value?

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When it comes to buying or selling a home, one of the first steps many people take is to check the estimated value of the property on Zillow. Zillow’s Zestimate tool provides a quick and easy way to get an idea of a home’s worth. But how accurate is Zillow home value? 

In this blog post, trusted Mesa AZ Realtor Lorraine Ryall dives deep into the factors that influence Zestimate accuracy, compares it with other valuation methods, and offers tips on how to use this tool effectively.

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whether to buy or to sell

What is Zestimate?

Zestimate is an automated home valuation tool developed by Zillow. It uses a proprietary algorithm that incorporates public data, user-submitted data, and MLS (Multiple Listing Service) data to estimate the market value of homes. The goal is to provide homeowners and potential buyers with a ballpark figure for what a property might be worth.

Factors Influencing Zestimate Accuracy

Data Quality

One of the most significant factors affecting Zestimate accuracy is the quality of data available. Public records can sometimes be outdated or incorrect, which can lead to inaccurate estimates. For example, if recent renovations or additions are not reflected in public records, the Zestimate may undervalue the property.

Market Conditions

Real estate markets are dynamic and can change rapidly due to various factors like economic conditions, interest rates, and local developments. Zestimates may not always capture these nuances in real-time, leading to discrepancies between the estimated value and actual market conditions.

Property Characteristics

Unique features of a property such as custom architecture, high-end finishes, or extensive landscaping may not be fully captured by an automated algorithm. These characteristics often require human judgment for accurate valuation. The human judgment of a qualified and experienced listing agent for example.

User-Submitted Data

Zillow allows homeowners to update their property information directly on its platform. While this feature can improve accuracy by providing more current data, it also opens up possibilities for errors or intentional misrepresentations.

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Comparing Zestimate with Other Valuation Methods

Professional Appraisals

A professional appraisal involves an in-depth evaluation by a certified appraiser who considers various factors like location, condition of the property, comparable sales in the area, and more. While more expensive than using an online tool like Zestimate (which is free), professional appraisals are generally considered more accurate because they involve human expertise. I explore this in more detail in my recent blog post that explores the differences between home valuation and home appraisals.  

Comparative Market Analysis (CMA)

Real estate agents often perform a Comparative Market Analysis (CMA) to estimate a home’s value based on recent sales of similar properties in the area. CMAs are usually more accurate than Zestimates because they take into account local market conditions and specific details about comparable homes.

Automated Valuation Models (AVMs)

Zestimate itself is an example of an Automated Valuation Model (AVM). Other AVMs include tools from Redfin and While these tools use different algorithms and data sources, they share similar limitations related to data quality and market dynamics.

How Accurate Are Zestimates?

According to Zillow’s own website:

National Median Error Rate: The median error rate for on-market homes is around 2.4%, meaning half of all Zestimates fall within 2.4% of the actual sale price. Not bad for a free automated tool but a potential difference of $12k on a $500k property.

Off-Market Homes: For off-market homes, the median error rate increases significantly to around 7.49% or $37,450 on a $500k property.

While these statistics indicate that Zestimates can be quite accurate for homes currently listed for sale, there’s still room for error—especially for off-market properties.

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Tips for Using Zillow Home Value Estimates

Cross-Reference Multiple Sources

Don’t rely solely on Zestimate when making important real estate decisions. Cross-reference with other AVMs like Redfin’s Estimate or’s valuation tools for a broader perspective.

Consult Professionals

Setting a selling price for your home or negotiation a buying price are deeply significant decisions. Zillow gives you a great first impression but before you take the critical next steps, consult real estate professionals such as agents or appraisers who can provide more nuanced insights based on their expertise. 

Update Your Property Information

Ensure that your property’s information on Zillow is up-to-date. Adding details about recent renovations or upgrades can help improve your home’s Zestimate accuracy.


While Zillow’s home value estimates offer a convenient starting point for understanding property values, they should not be relied upon exclusively due to their inherent limitations related to data quality and market dynamics. By cross-referencing multiple sources and consulting professionals, you can make more informed real estate decisions and make wise investment decisions.

In summary: How accurate is Zillow home value? It depends—but with careful consideration and additional research, you can use this tool effectively as part of your overall strategy in navigating the real estate market.

When your ready to consult a professional, contact me to achieve your real estate goals in Mesa AZ.

Lorraine Ryall, Associate Broker, Mesa AZ

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