Skip to main content

Zillow algorithm overestimates Seattle home’s value by 700 percent

Zillow may just be a seller’s best friend (but certainly not a buyer’s). According to a recent report from the Seattle Times, the popular online real estate database somehow managed to overvalue a Seattle home by a whopping 700 percent.

Recommended Videos

The home, which owners Sue and Roy Carlson purchased in June 2017, cost the couple just $225,000 (a particularly good deal because the property was initially slated for foreclosure). Other real estate companies (think Redfin and Realtor.com), now show the value of the home as somewhere between $268,000 and $318,000. Zillow, on the other hand, says that the property is worth $1.8 million.

Please enable Javascript to view this content

Thanks to some serious SEO magic on Zillow’s side, when you Google this home’s address (like most home addresses), it’s the Zillow result (or Zestimate) that returns first. And that means that the first thing that most folks are seeing when they look into the Carlson’s home is a valuation that is seven times what just about everyone else on the market thinks it ought to be.

“I don’t have a clue where they came up with this number,” Sue Carlson told the Seattle Times. “It’s not worth anywhere near $1 million. They’re nuts.” She added, “If anybody wanted to buy the house (and saw the $1.8 million Zestimate), they would just go, ‘Well, that’s ridiculous.’”

Carlson then took a deep dive to determine exactly how Zillow might’ve arrived at its hugely inflated figure, and as the Times notes, “Her story offers a peek into how algorithms can go wrong, and highlights an ongoing issue with one of Seattle-based Zillow’s most popular features.”

As it turns out, Zillow admitted in 2017 that its Zestimates are generally off by around $40,000 when considering the “typical single-family home sold in Seattle.” In fact, when the company’s own CEO Spencer Rascoff sold his own house in 2016, the Zestimate was too high by a factor of 40 percent. Moreover, the house he ultimately purchased was misestimated by more than $1 million.

 These issues have led to some lawsuits, as well as a number of attempts by Zillow to improve its estimation process. In fact, the company last year launched a competition with $1 million prize in prize money to better the Zestimate algorithm (the company recently announced 100 semifinalists who have already made some small improvements to the platform).

The case of the Carlson’s home, however, is particularly outlandish. The problem was that Zillow somehow recorded the actual sale price of the home when the Carlsons bought it as $1.77 million. This, a spokesperson said, was not a fault of Zillow’s, but rather of a third-party vendor who incorrectly supplied sales data. Zillow has since fixed the actual sale price, and the Zestimate should soon be corrected as well.

“Overall, the Zestimate is incredibly accurate — with a median error rate of 4.5 percent — but occasionally human error does occur,” Zillow spokesman Viet Shelton said in a statement. “Since the Zestimate is calculated using thousands of data points, it’s only as good as the data provided.”

Lulu Chang
Former Digital Trends Contributor
Fascinated by the effects of technology on human interaction, Lulu believes that if her parents can use your new app…
Digital Trends’ Top Tech of CES 2025 Awards
Top Tech of CES

Las Vegas is overrun. Every billboard in town is shouting about AI, hotel bar tops now sport a sea of laptops, and after hours The Strip is elbow to elbow with engineers toting yard-long beers.

That means CES, the year’s biggest tech bacchanalia, has come to town, and Digital Trends editors have spent the last four days frolicking among next year’s crop of incredible TVs, computers, tablets, and EVs. We’re in heaven.

Read more
Ring shows off new Kidde smoke alarms and free 2K camera upgrades at CES 2025
A person setting up a Ring Smoke Detector.

Ring made a big -- though rather surprising -- announcement at CES 2025, revealing that it has partnered with Kidde to launch a new collection of smart smoke alarms. Arriving in April, the collection includes the Kidde Smart Smoke Alarm and Combination Alarm, the latter of which detects both smoke and carbon monoxide. They’ll sync with the existing Ring app to send users alerts should anything trigger its sensors, and they should be an enticing option for folks who have already bought into the Ring ecosystem.

While customers will receive alerts via the mobile app, they can also sign up for the new Ring 24/7 Smoke & CO Monitoring Subscription for $5 per month. This is a professional monitoring service that lets a trained dispatch team keep tabs on your detectors -- and if they’re triggered, the dispatch team can automatically contact emergency services and send them to your home. That should provide more peace of mind than your normal smoke alarms, which might ring out loud and clear but can’t alert the fire department.

Read more
Jackery’s new solar panels are indistinguishable from your roof
jackerys new solar panels are indistinguishable from your roof jwholehome

When you think of solar panels on a home, what's the first thing that comes to mind? In most cases, it's the square, black photovoltaic cells. While those do work, they aren't the most aesthetically pleasing. This is an issue, especially in communities with draconic HOAs. The Jackery Solar Roof offers an attractive alternative that's practically indistinguishable from terracotta roofing tiles.

The Solar Roof has a conversion rate of over 25%. That might not sound like a lot, but the average efficiency rating of solar panels is typically between 15% and 22%, putting Jackery far ahead of the pack. These panels are tougher than a normal roof, too; they're impact and hail resistant and come with a 30-year warranty. That's right, 30 years (and the average lifespan of a normal roof is only 20 years).

Read more