In the year since its launch, Zillow Inc. has made millions of home buyers familiar with computer-generated estimates of home values.  On numerous occasions I have had potential buyers ask me about a "Zestimate" they had seen by looking at the Zillow web site.   But just how accurate is it?  

As a test I went to Zillow and posted one of my own listings to see what it came up with.  The home I posted is 9669 Eaton Woods Place in Lorton Virginia.  As soon as I posted the home I saw a number of errors.   The number of bedrooms, bathrooms and square footage was wrong! The second thing I noticed was that the tax record-what it is using for the "Zestimate" was using the 2006 tax record not 2007.  In this case the tax value of the property has risen $16,120 since last year.  The third thing is that it does not reflect the most recent sales.  A neighboring home 7909 Gunston Woods Place just sold on March 2 for $430,000.

So then I went to the most recent MRIS statistics for the 22079 zip code to determine whether the Zillow graph which indicates a 30 day value trend down 2.1% was on target.   Opps wrong again.  For the month of February 2007 the average sold price was up 5.33% over the same period in 2006.  Yes, I know it is taking longer for a home to sell and the number of homes available for sale is higher but it doesn't mean that in every area the values are down significantly.

I have been able to correct some of the general information about the property on Zillow so that at least if someone pulls up the property to look at it they will see some accurate data about the home.  However the Zestimate will continue to be wrong as will their graph on the trends in home values for this area.

So what do you do?  If you are a buyer you need to understand that Zillow does not know the local market.  It doesn't know the condition of the house you are interested in, it doesn't know the pros or cons of a specific neighborhood and it certainly isn't there to represent you in the purchase of the home.  That is what a good buyer's agent can do for you.