When you are searching for homes on Zillow.com, there is often a chart at the bottom of the page that shows the market value estimate or Zestimate® for that property and the surrounding area. How good are those estimates? Here is the data from the tri-county area of Lansing, MI. There are many factors affecting these estimates, in addition to those not accounted for by computers & mathmatical formulas. Feel free to contact me for more information or a market analysis on your property.