In my opinion as a real estate agent, Zillow.com can be a helpful tool for consumers for ball-park property valuation but should not be relied upon to provide exact opinions of value. Read the small print on Zillow.com and they will tell you the same thing. Check out their FAQ page.
The reason zillow is unreliable for property valuation is that no algorithms or mathematical formula can accurately predict a property’s value especially in a mountain community such as Estes Park where properties can vary tremendously. For instance, it is impossible to compensate consistently for many factors that influence property value including quality of construction, quality of materials used, views, privacy, neighbor quality, neighbors pets, nieghbors recreation habits, paint color, sun exposure, bright or dark interiors, smells, future events, room flow, landscaping, pests, and more.
Zillow.com discloses these variances on their website in specific markets. Unfortunately, they do not disclose the variance for communities as small as Estes Park, Colorado. In Denver, in a location where the majority of homes are in subdivisions with consistent values, the zestimate (zillow’s estimate of value) was off more than 10% of the actual selling price more than 55% of the time. Over all, zestimates have a history of having an 11.6% margin of error in Denver. See this page on zillow.com talking about accuracy.
As a real estate agent, I wouldn’t be in business very long if I estimated property values with an 11.6 percent average margin of error. Do yourself a favor and get the opinion of a local real estate agent or appraiser to establish market value. Otherwise, you run the risk of making very important decisions based on inaccurate data.