Are Zillow Zestimates accurate or inaccurate, or somewhere in between? This is a big question all across the United States, and it’s a hot topic. Some homeowners are downright angry at how Zillow Zestimates have underestimated the value of their home while they are trying to sell it. Some buyers came to rely on Zillow Zestimates as they looked at homes and thought about drafting offers, and some got burned as a result. So what’s the truth about Zillow Zestimates? I’ll answer that question now.

Zillow Zestimates: What They Are

Zillow Zestimates

Zillow Zestimates are created by software that scrapes data off the Internet, including sales data of similar homes, tax assessor data, sold data, and MLS listing data. Zillow’s computers compile all the data based on programming, and statistics are generated, including the now infamous Zillow Zestimates.

Sometimes their estimate is right on, but other times it is way off. I personally experirenced a Zestimate that was over $300,000 off. The homeowner was quite upset at Zillow. The CEO of Zillow found out how far off his Zestimate was. CEO Spencer Rascoff’s home sold for 40% less than the Zillow estimate of $1.75 million. I think I’ll just say, “Oops!”

Rascoff also bought a 12,732-square-foot mansion in LA’s affluent Brentwood neighborhood for nearly $20 million, which happened to be over $1 million above its Zestimate. And Zillow wants you to rely on Zillow Zestimates? Are they serious? 

Zillow apparently uses refinance information as part of their algorithm. Here’s a personal testimony of a homeowner who discovered this about his own home:

One other BIG reason why Zillow’s Zestimate can be (way) off is that they display and include REFINANCES for their “guesstimation” of value. How do I know that? Because I just checked on my own home and my refi that I did in December of last year shows up as a SALE. That’s a problem – nevermind untrue and misleading – since it impacts Zillow’s opinion of the value of my home and comparable homes in my subdivision. I did not sell my house. I did not refinance at 100% value. I brought cash to the table to lower my mortgage amount and monthly payment. My house appraised for much more than I refinanced for. But Zillow does not know that. [Source]

Zillow Zestimates: What They Are Not

What Zillow Zestimates are not is a much longer explanation than what they are. Here’s what we can say for sure what Zillow Zestimates are NOT. They are not appraisals. An appraisal is completed by a person who is educated and certified by an Appraisal Institute or an Appraisal organization of some kind, and appraisals are required by banks and mortgage companies to value a property accurately. An appraiser is the single professional most relied upon to estimate the value of a home. The CEO at Zillow has admitted that Zillow Zestimates are definitely not appraisals.

When a Realtor does a CMA, or a comparative market analysis, he or she uses carefully selected homes that are similar in size, architecture, age, square feet, the number of bedrooms and bathrooms, the property acreage, and the neighborhood. The Realtor doesn’t just randomly choose homes that appear to be similar–he or she has actually seen some, if not all, of the homes that are being compared. This means the Realtor can make distinctions in the quality of materials used to build a home, the special features, the view from the windows, and so on. Zillow Zestimates cannot make these kinds of distinctions, and no human beings are involved with the primary home or the comparables when Zillow’s algorithm crunches numbers. So we can say definitively that Zillow Zestimates are not CMAs.

Lastly, Zillow Zestimates are not official tax assessor values, which are conducted with very customized local software, a hands-on approach by local assessors, and with feedback from homeowners who can challenge assessed values that are above fair market value.

Now I’m going to tell you something few people know. Zillow has stolen most of its data that it now houses on its servers, and that it uses to create Zillow Zestimates. I know, that may surprise you. Most people do not know that MLS (multiple listing service) property data and photographs and virtual tours are the property of the homeowner who listed with a Realtor, and the Realtor and his local MLS have an ownership interest when a homeowner signs a listing agreement. Note that homeowners have not given Zillow permission to use the information about their home and property, and local MLSs or real estate associations have not given Zillow permission to use all the data. When a listing agent takes photos and pays for a virtual tour, guess who owns those photos and the virtual tour (and maybe drone video)? The listing agent owns all that, not Zillow. Unless Zillow has a written agreement to use all of that, they have used it without permission, i.e. stolen it.

I talked with the Clallam County Tax Assessor years ago about how Zillow was scrapping assessor databases and using it for their business. The tax assessor told me that all the data they had in their database on properties belonged to them with the permission to use it by property owners, and that Zillow, or any company, would have to sign a written agreement authorizing them to use the tax assessor’s data. He told me Zillow had never signed any such agreement, and therefore was scrapping everyone’s property data without permission, i.e. stealing it.

Why doesn’t someone stop Zillow? Who? Small MLSs or real estate associations don’t have the money to pay attorneys to go up against a billion dollar company, and neither do county assessors. So Zillow does what it wants with your private information, and makes money by selling real estate agents advertising space and leads.

The bottom line is that Zillow Zestimates are not reliable for sellers or buyers. If you love Zillow, go ahead and use it, but understand that not only has there been problems with the inaccuracy of information on properties all over the United States, the Zillow Zestimates are statistically not reliable.

This is probably the biggest reason to use a local MLS site that is accurate and does not attempt to value properties by scrapping data off the Internet and crunching numbers without any human beings. For the Sequim area, the best MLS site is It is 100% accurate and reliable. And you can always call upon local experts for help on values and viewing homes. 

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