A Zillow Zestimate is generated by an algorithm that uses publicly available data, past sales, tax records, and general market trends, to estimate value. It doesn’t account for the condition of your home, any improvements you’ve made, your lot characteristics, or what’s happening at the street level in your specific Monroe neighborhood. A Comparative Market Analysis, by contrast, is prepared by a licensed agent using actual sold data from the Fairfield County MLS. It compares your home to properties that are genuinely similar, in size, condition, location, and features, and reflects the current negotiating environment. The difference can easily be $30,000 to $60,000 in a market like Monroe’s.