How accurate are Zillow’s Zestimates?

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[Ed. Note: A more recent blog post on this topic (published December 26, 2017) can be found here: How Accurate is Zillow’s Zestimate?]

I’m frequently asked what is the accuracy of Zillow’s Zestimates.  Yesterday, I sat in at a seminar presented by some guys from Zillow.  They stated that their Zestimates have a median error rate of ±8.5 percent nationally.  However, the accuracy rate varies greatly by County.

Did you know, that Zillow monitors and tracks the accuracy of their Zestimates constantly, and reports these numbers for areas across the country?  Check out Zillow’s About Zestimates link and drill down to the state, county, or metro area of your choice.

For example, I looked up Washoe County, Nevada and found that the error rate of Zillow’s Zestimates for Washoe County to be ±5.9 percent.

About Guy Johnson

I am a licensed Nevada REALTOR® living and working in Reno, Nevada. Give me a call at 775-722-4011. My team and I will be happy to assist you with your real estate needs.
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9 Responses to How accurate are Zillow’s Zestimates?

  1. Tom says:

    The formulation for the `Zestimate’ can produce strange variations among neighboring houses of the same age, style and size, depending upon the sales history of each. If there is a house which has no sales history, because it has been owned since built by the developer by one family, with no changes of ownership for thirty plus years, and it happens to be in a Proposition Thirteen type of jurisdiction, that property will have a very low assessed valuation and low property taxes. Zillow’s formulation takes into account public information, and assessed valuation is a part of this, and works it through its algorithm from there. If your house happens to have a very old and low assessed valuation, when the Zestimate factors trend that value forward in time, a disparity can arise between your house and an adjoining property which has a recent sale in its history. Recent sales and reassesments of valuation impact the Zestimate. In our neighborhood, our house was valued less by Zestimate than adjoining houses which were all built by the same builder, at the same time, same style and same project, on the same street. The neighboring houses had recent sales, giving the formulation a higher base point to work upon, whereas our starting point was our original purchase price of 33 years ago. Our assessed value has not changed, other than the limited amounts each year under Prop. 13. So the Zestimate software in my view while interesting and in some ways useful, can be off significantly for a property with no sales history, in a jurisdiction where assessed value and property taxes are not significantly increased until a sale occurs.

  2. Transplant says:

    It’s always amusing (to me, at least) when you find a listing with a >$100K disparity between the Zestimate and the seller’s asking price.

  3. Michael Helton says:

    I recently witnessed 3 Realtor estimates with a $100,000 range…on a $350,000 property! I am sure we have all seen how variable appraisals can be; even from local experts. So, for a free tool Zillow is pretty sweet.

  4. Rick says:

    I would love to get what Zillow says my house is worth! Most folks complaining about the site and the Z-estimates are doing so because they fear that Zillow is UNDER estimating their home value. My concern is that it is indeed inaccurate, but because it is OVER estimating. I guess I’ll only know when I go to list it.

  5. J. Nelson says:

    I live in a group of identical custom patio homes in Houston, TX. I noticed that for some reason my house was on Zillow for 40K less than my neighbor with a smaller house than is in bad shape. I send an Email to Zillow asked them to correct the discrepancy. Zillow proceded to reduce the value of my house by another 60K instead of making it at least equal to the others in the cluster of homes. Now my house is listed on Zillow as being $110,000 less than my neighbor with a house 400 ft2 smaller. The zillow price is now $30,000 less than the Harris County appraisal district price. I have sent them 10 emails trying to get them to correct this. They never answer the Emails. If any of you believe any of the house values on Zillow you are retarded.

  6. J. Mackey says:

    Im wondering if mine is under because they also have others near me that are smaller and older and are appraising for more than mine. I have a 2 yr old town home and it’s appraising me at 78k but there was ones selling in my neighborhood who have the same plan as me for 115-130. I don’t get it. I really dont want to believe it.

  7. Twister says:

    Zillows estimates confound me half the time and can be wildly off the mark in some cases. I sure wouldnt use their Zestimate as a price to sell.

  8. Mrs. Right says:

    Just want to say, we bought our 2nd house for $30,000 more than the Zestimate….yet the taxes and county GIS appraised and still taxes us at $90,000 more than we paid… Just sayin’

  9. George says:

    I like to point out that Zillow Zestimate has a magic wand that overnight wiped out several millions dollars of home value in our neighborhood on their website. It happened Wednesday afternoon.

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