How Accurate are Zestimates?
If you're a homeowner, you might keep track of your home's value by using Zillow's "Zestimate" tool or use it as a gauge to determine the sale's price for your house. But are Zestimates accurate?
A Zestimate is Zillow's estimated market value for a home, computed using a proprietary formula that includes public and user-submitted data. The proprietary formula uses information from tax assessments and public records, real estate brokerages, and the multiple listing service (MLS), then compares that data to similar homes that sold nearby, known as comparable homes. The algorithm behind the Zestimate uses sophisticated machine learning models to process this vast amount of data.
Zillow does not claim that the Zestimate is 100% accurate. It lists the median error rate on its website, which is the margin of error from the estimated value to the actual value. As of mid-2025, Zestimate's median error rate for on-market homes nationwide is 1.9%, meaning that half of all for-sale homes are within 1.9% of the ultimate sales price, and half are not. For off-market homes, the median error is around 7.0%.
The Zestimate's accuracy depends on location and the availability of data in the area. Markets without widely available market data or limited sales activity might see a more significant margin of error than markets with consistent sales activity and an abundance of market data.
Zestimate Limitations
The Zestimate considers the home's square footage, location, bed and bath count, age, and lot size. However, Zestimates are only as accurate as the data they rely on, which can sometimes be outdated. For example, updates or upgrades made to a house that are not public record will not reflect in the Zestimate unless a user submits them. Homeowners can directly update their home's facts on Zillow's website to improve the Zestimate's accuracy.
Zestimates also don't consider the condition of a property or its unique features, which are critical when determining a home's value. If the house needs repairs or has certain features that take away from its value, then the Zestimate could be higher than the property's actual value. Conversely, a new kitchen or a beautifully landscaped yard might not be factored in, causing the Zestimate to be lower than the true market value.
If the property is in good condition and the local market has seen consistent activity over the past several months, the Zestimate will be more consistent with the actual value of the property.
The Best Way to Determine a Home's Value
While a Zestimate is a useful starting point, it's not a replacement for a professional valuation. If you're interested in determining your home's actual value, then it's best to hire an appraiser or a qualified real estate agent to give you their professional opinion.
A real estate agent can perform a Comparative Market Analysis (CMA), which is a free report that analyzes recently sold, active, and expired listings in your area. They will study the local market, walk through the house to evaluate the property's condition and unique features, and compare it with recent sales to provide an informed valuation.