Zillow’s property value estimates, commonly referred to as “Zestimates,” may be misleading Illinois home buyers. With a median error rate of approximately 8 percent nationwide, and even higher in some areas, these inaccuracies can equal disparities of tens of thousands of dollars. In some situations, the difference between a Zestimate and a true property appraisal is more than $100,000.

Zestimates Are Not Actual Appraisals

A Zestimate is a very popular consumer tool used to estimate a home’s worth. According to Zillow, these property value approximations are not true appraisals, and they do not claim to be. They are actually computer-generated estimates that use public data, neighborhood information, and records from property-tax sites to determine a home’s value. By entering the address or location information of real estate, consumers can access information about active property listings as well as those not currently on the market. As their implies, however, Zestimates are not precise.

Why Are Zestimates Inaccurate?

There are a number of reasons that Zillow Zestimates may be inaccurate.

• Basic Information: Zestimates are based on public data and user-submitted information. If the information used to generate an estimate is incorrect, the Zestimate will likely be off as well.
• Unique Features and Upgrades: Zillow doesn’t always know about unique features and certain upgrades that can significantly affect a home’s value. A completely updated kitchen or bathroom, for example, can make a home more attractive to home buyers and raise the home’s value, but if the remodel isn’t on the record, the Zestimate won’t reflect it.
• Comparable Homes: Since part of what determines a Zestimate is an information about other, comparable homes nearby, any mistakes or omissions regarding those homes can trigger a substantial inaccuracy.

How Inaccurate Are Zestimates?

According to MarketWatch, the accuracy of Zestimates varies by location. Even Zillow concedes that Zestimates should only be used as a starting point in determining a home’s value and are not completely accurate. Overall, these property estimates are within 5 percent of an actual sale price just 54 percent of the time. They are within 10 percent about 76 percent of the time, and approximately 90 percent of the time they are within 20 percent of a sale price. In Chicago, a Zestimate is within 5.9 percent of an actual sale price just more than 44 percent of the time.