Many homeowners use Zillow as a way to find out the value of their home when they are thinking of selling. Home buyers use Zillow to decide if a house listed for sale is overpriced.
In some parts of the country, Zillow is a good way to determine home value.
But not everywhere.
How Accurate is Zillow?
Zillow is completely upfront in disclosing there is a margin of error on every home value on their website.
Since the information available to Zillow is incomplete, there is no way that their computer calculations can provide a definitive value. They even claim on their own site that the Zestimate is only designed to give you a starting point for evaluating the value of a home.
What’s a Zestimate?
A Zestimate home valuation is Zillow’s estimated market value. It is not an appraisal. Use it as a starting point to determine a home’s value.
The Value Range is the high and low estimate market value for which Zillow values a home. The more information, the smaller the range, and the more accurate the Zestimate.
They don’t have information on if the home is updated or not. They don’t know if the house backs to a busy street, if the owners painted the shutters pink or the bedrooms are so small they can barely hold a bed.
Even more important, they don’t know if the similar sized homes that recently sold nearby are in nicer or less desirable subdivisions.
Without all of this information, how could Zillow possibly provide an accurate value for homes?
How Accurate is Zillow for St. Louis?
A few years ago, Zillow reported that their Zestimate was only within 20% of the sale price for 3 in 4 St. Louis homes.
An example based on Zillow’s own reported accuracy for 2011:
- $200,000 sale price
- only 3 in 10 would have been estimated from $190,000 – $210,000
- only half would have been estimated from $180,000 – $220,000
- 3 in 4 would have been estimated from $160,000 – $240,000
Today, Zillow won’t even report how accurate their numbers are, presumably because they don’t like how inaccurate they are when they compare their Zestimates to actual closing prices for sold homes.
Why Can’t Zillow Know How Accurate They are for St. Louis?
I really don’t understand how Zillow can’t report an accuracy rating for a city in which almost all of the homes listed on Zillow have a Zestimate score. If they can compute an accuracy rating for one city, they can do it for all of them.
The truth is that they CAN compute an accuracy score for St. Louis homes, they just don’t like the numbers so they opt to not report it. Instead, they gave St. Louis a 1 star rating and use the local tax assessor’s value rather than continuing to take responsibility for low accuracy ratings themselves.
How Accurate are Tax Assessor Home Values?
Since Zillow is pulling the local tax assessor home values and reporting that as the home value Zesimate on their site, let’s take a look at how inaccurate the tax assessor values are in St. Louis.
Below is a list of homes that all sold in St. Louis County in June 2014 for the exact same price. I eliminated foreclosures, probate, auctions and short sales, so none of these sales were distressed and selling at a big discount as a result.
St. Louis County June 2014 sales – $250,000 Sale Price:
- 12915 Somerton Ridge Dr (Creve Coeur) – tax assessor market value $298,100 (19% OVERVALUED)
- 1818 Summer Lake (Chesterfield) – tax assessor market value $214,500 (14% undervalued)
- 426 Dana Meadows Ln (Ballwin area) – tax assessor market value $175,200 (30% undervalued)
- 1256 Willow Creek Ln (Rock Hill) – tax assessor market value $185,400 (26% undervalued)
- 4620 Aspen Hollow Dr (South County) – tax assessor market value $213,700 (15% undervalued)
- 104 Denbigh Terr (Ballwin) – tax assessor market value $221,900 (11% undervalued)
- 276 Geremma (Ballwin) – tax assessor market value $153,600 (39% undervalued)
- 207 Ranchmoor Trail (Ellisville) – tax assessor market value $189,500 (24% undervalued)
As you can see, St. Louis County routinely undervalues homes, but there is a wide range in the tax assessments. In addition, you will occasionally find homes that are overvalued (in which the homeowners having been paying too much real estate tax!).
Since Zillow uses the tax assessor values for St. Louis homes on their website, the only way to know the true market value of a particular home is to have a real estate agent or appraiser evaluate recently sold properties in comparison to the home.
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