We need to talk about that number.

You know the one. You’ve pulled up Zillow at least once—probably more like a dozen times—and looked at the Zestimate on your home. Maybe it made you feel great. Maybe it made your stomach drop. Either way, I’m willing to bet you remember it. And if you’re thinking about selling, there’s a decent chance that number is sitting in the back of your mind like some kind of gospel truth.

Here’s the problem: it’s not. And the question of how accurate the Zillow Zestimate really is has an answer that might surprise you.

I’m not saying that to be dramatic. I’m saying it because the data backs it up—and some of that data comes from Zillow themselves. So let’s break this down, because if you’re planning to sell your home in Sarasota or anywhere in Southwest Florida, you deserve to understand what that number actually is, where it comes from, and why leaning on it could cost you tens of thousands of dollars.

Zestimate Accuracy: The Numbers Zillow Hopes You Won’t Look Too Closely At

Zillow publishes their own accuracy data, and to their credit, it sounds pretty good at first glance. They report a median error rate of about 1.83% for homes currently listed on the market. Not bad, right?

But here’s the catch—and it’s a big one.

Your home probably isn’t on the market yet. You’re checking the Zestimate before you list, which means you’re looking at the off-market number. And for off-market homes? The median error rate jumps to over 7%.

On a $500,000 home, that’s a $35,000 mistake in either direction.

And “median” means half of all estimates are worse than that. In some markets, over 20% of Zestimates miss by more than 20%. In Tampa—right next door to us here in Southwest Florida—about 16% of estimates miss by that much.

So when someone tells me, “Zillow says my house is worth $650,000,” what I hear is: “An algorithm that’s never been inside my house generated a number that could be off by $45,000 or more, and I’m about to use it to price the biggest sale of my life.”

That should make you nervous.

The Story Zillow Really Doesn’t Want You to Know

Let me tell you my favorite part of this whole saga, because you can’t make this stuff up.

In February 2016, Zillow’s own CEO at the time—Spencer Rascoff—sold one of his properties in Seattle. The sale price? $1.05 million.

The Zestimate on that same property the very next day? $1.75 million.

That’s a 40% error. Seven hundred thousand dollars wrong. On the CEO’s own house.

And what did Rascoff say about it? He told reporters, “We call it a Zestimate, not a Zeppraisal.” When he went to buy his next home, he used a real estate agent—not his own company’s algorithm.

Zillow’s Chief Analytics Officer, Stan Humphries, was even more direct. He admitted publicly that “the slight edge does go to humans over automated valuation models when it comes to pricing a home.”

Read that again. Zillow’s own data chief said humans are better at pricing homes than their algorithm.

Zillow Lost $881 Million Trusting Their Own Algorithm

But wait—it gets better. Or worse, depending on how you look at it.

In 2018, Zillow got so confident in their algorithm that they decided to put real money behind it. They launched a program called “Zillow Offers,” where they would buy homes directly from sellers using the Zestimate to determine the purchase price. The idea was simple: buy homes, do minor repairs, flip them for a profit. They had the best data, the best engineers, and more computing power than any real estate company on the planet.

They literally bet the company on their own algorithm.

Three years later, in November 2021, they shut the entire program down. The damage? $881 million in losses. Roughly 2,000 employees—about 25% of the entire company—were laid off.

CEO Rich Barton summed it up: “The unpredictability in forecasting home prices far exceeds what we anticipated.”

They were stuck with thousands of homes they’d overpaid for and couldn’t sell.

Think about that for a second. Zillow—with all their data, all their engineers, all their money—couldn’t make their own Zestimate work when actual money was on the line. They lost nearly a billion dollars trying.

So why would you trust that same algorithm to price YOUR biggest asset?

What Zillow Can’t See (And It’s a Long List)

Here’s the thing, and no amount of better technology is going to fix it: Zillow has never been inside your house.

It doesn’t know you just finished a $50,000 kitchen renovation with quartz countertops and new cabinets. It doesn’t know you installed impact windows throughout the entire house—which, here in Florida, is a massive selling point that buyers will pay a premium for. It doesn’t know your HVAC is brand new with a 10-year warranty, or that you re-piped the whole house with PEX last year.

And it works the other way too. It doesn’t know that your neighbor’s home—one of the “comparable sales” it’s using—sold $30,000 under market because the seller was going through a divorce and needed to close fast. It doesn’t know about seller concessions that knocked the real price down but don’t show up in public records.

The Zestimate is built on tax records, public data, and whatever the algorithm can scrape. It’s looking at your home value from 30,000 feet. It has no idea what’s happening inside.

Why Zillow Home Values Are Especially Unreliable in Sarasota and Southwest Florida

Now let me get specific, because selling a home in Sarasota, Manatee, Charlotte, or Lee County isn’t like selling a home in Ohio. We’ve got things going on down here that no national algorithm is built to handle.

The insurance crisis. Florida homeowners are paying an average of $5,700 per year for property insurance—the highest in the nation. And it gets worse: if your roof is over 15 years old, insurance companies can require an inspection proving it has at least five more years of useful life before they’ll write a policy. That directly affects what a buyer is willing to pay for your home, because it changes what they’ll pay every single month after they buy it.

Does Zillow know your roof’s age? Does it know what your insurance situation looks like? Does it factor in the $2,400 difference between what one neighborhood pays and another? No.

Flood zones. FEMA has updated their flood maps, and thousands of homes in our area are now in high-risk zones that weren’t designated that way before. Flood insurance can add $2,000 to $5,000 or more annually, and Citizens Insurance is requiring flood coverage for more and more properties. Buyers are doing this math. Zillow’s algorithm isn’t.

Hurricane psychology. After Hurricane Ian, Lee County home values dropped 10–16%. Sanibel went from an average of about $1.4 million before the storm to around $980,000. The majority of sales in Fort Myers Beach were coming in under list price. An algorithm can’t capture whether people feel safe buying in a particular area. That’s buyer psychology—and it’s very real, very local, and completely invisible to a computer.

What to Do Instead of Trusting the Zestimate

If you can’t rely on Zillow, what’s the move?

Get a Comparative Market Analysis from a local agent. And I don’t mean someone who pulls three comps and calls it a day. A good CMA is real work—it looks at what actually sold in your area, adjusts for the specific differences between those properties and yours, accounts for current market conditions in your neighborhood, and factors in what buyers are actually looking for right now.

At K&C Group, we go a step further. We’ve built proprietary tools—a CMA Improvement Value Guide and a Construction Cost Guide—that let us quantify exactly what your specific upgrades are worth. Not guesses. Data. Your impact windows, your new roof, your kitchen remodel—we can tell you what those improvements actually add to your home’s value, backed by real numbers.

You can also consider a professional appraisal. A licensed appraiser will physically walk through your property. Banks require appraisals for a reason. A $400–$800 investment can prevent a $50,000 pricing mistake.

The Bottom Line

The Zestimate is fine for scratching that itch—think of it like checking the weather app. But you wouldn’t plan a major outdoor event based solely on a forecast from two weeks ago. Don’t price your home based on an algorithm that’s never seen it.

Zillow’s own CEO learned this the hard way when his home sold for 40% less than the Zestimate. The company learned it the hard way when they lost $881 million trusting the algorithm. You don’t have to learn it the hard way too.

Your home is probably your biggest asset. Don’t price it with a guess. Get real data from someone who knows the Sarasota and Southwest Florida market.

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If you’re thinking about selling in Southwest Florida and want to know what your home is actually worth—not a Zestimate, but a real analysis backed by real data—K&C Group offers complimentary Comparative Market Analyses.

Ready? Schedule your complimentary CMA

About the Author

Eric Konoski is Team Lead and Broker Associate for K&C Group at eXp Realty, serving Sarasota, Manatee, Charlotte, and Lee Counties. A retired NYPD Captain, Eric brings an investigative, evidence-based approach to every transaction. K&C Group specializes in luxury and premium properties across Southwest Florida’s Gulf Coast.