Zillow vs. Reality: How accurate are Zestimates in the Tri-Cities?

Introduction: Zillow vs Reality

For five months this year, we compared the Zestimate of homes sold across the Tri-Cities with their actual sales price. What follows is a full report and recap of our data. In this study, you’ll learn that:

  • The Zestimate of a typical Tri-Cities home is almost 6 percent higher than the home’s actual sales price.
  • Pasco has the most accurate Zestimates in the Tri-Cities.
  • Tri-Cities’ Zestimates are more than twice as inaccurate as Zestimates across the state.
  • The more expensive a Tri-Cities home is, the more inaccurate its Zestimate is.

How Zillow’s Zestimates Work

Zillow’s “Zestimate” is a computer-generated estimate of a home’s value. Zillow’s algorithm relies on all the available data it can find about a home, from sources that include public tax records, information from multiple listing services and real estate brokerages. It also accounts for a home’s “facts and features,” like the size and location of the home, and how many bathrooms it has. Zillow’s algorithm also incorporates the local real estate market — recent sales of comparable homes and how long homes are on the market.

When Zillow launched in 2006, the company says it had a median error rate of 13.6 percent — meaning half of all Zestimates were within 13.6 percent of a home’s final sale price. That number has improved over the years. In January 2019, when Zillow announced the winners of a competition where programmers sought to improve the algorithm, the company said its median error rate was 4.5 percent. (Meaning half of all Zestimates were within 4.5 percent of the actual sales price.)

Studying Zillow’s Accuracy

Zillow itself tracks the accuracy of Zestimates across the U.S. and publishes the data on its website. The tracker focuses on 30 “top metro areas” — Seattle and Portland are included, but mid-sized markets like Spokane aren’t. And that means a smaller market like the Tri-Cities is missing, too.

With that in mind, early this year we began to study the accuracy of Zestimates for Tri-Cities homes. On a nightly basis, we charted the home sales that closed that day and recorded both the actual sale price and the Zestimate as published on Zillow. (Here’s a full look at our methodology.) Our goal was to educate ourselves and local home buyers/sellers about the accuracy of Zestimates in the Tri-Cities. The more we understand about Zestimates and real home values, the better we can serve our clients.

The results of our study are presented here. We’re reporting the data for the Tri-Cities area overall, as well as for each individual city tracked. You’ll also find data comparing Zestimate accuracy with the price of homes. If you only have time to read one page, see the “Key Takeaways” link below for a summary.


At the bottom of each page, you’ll find this list of pages that can be visited in whatever order you like.

  1. Zillow vs Reality: Introduction (this page)
  2. Zillow vs. Reality: Key Takeaways
  3. Zillow vs. Reality: All Tri-Cities Home Sales
  4. Zillow vs. Reality: Kennewick
  5. Zillow vs. Reality: Pasco
  6. Zillow vs. Reality: Richland
  7. Zillow vs. Reality: West Richland
  8. Zillow vs. Reality: Home Value Comparisons
  9. Our Methodology