Why the Zestimate Is Inaccurate and What to Use Instead

The Zestimate is Zillow's computer-generated estimate of a home's value. It's a reasonable starting point, but for any single home it can be off by a lot, and Zillow itself says it isn't an appraisal. Here's why, and what to use instead.

How the Zestimate works

Zillow's model uses public records, recent sales nearby, listing data and details owners add, such as bedrooms, bathrooms and square footage. It estimates what similar homes in the area have sold for and adjusts for differences.

Why it gets things wrong

• It can't see inside: a renovated kitchen and a home needing a new roof can look the same in the data.
• Wrong records: outdated square footage or missing additions throw the estimate off.
• Few comparable sales: rural areas and unusual homes have little data to compare with.
• Location details: a busy road, a view or a school boundary can change value in ways the model may miss.
• Fast markets: sales data lags, so estimates trail sudden rises and falls.

Zillow publishes its own error rates, and they're much lower for homes currently for sale than for off-market homes, because the list price gives the model a strong clue.

Is the Rent Zestimate accurate?

The Rent Zestimate has the same limits, plus fewer data points, since many rentals are never listed publicly. Check it against current listings for similar homes nearby before setting a rent or buying an investment property. See the Rent Zestimate for investors.

What to use instead

1. Comparable sales: homes of similar size, age and condition that sold nearby in the last three to six months. Recent sales matter more than current asking prices.
2. A comparative market analysis (CMA): a real estate agent can prepare one from local sales data, usually free if you're thinking of selling.
3. An appraisal: a licensed appraiser's opinion of value, which lenders require. It costs money but is the most rigorous option.
4. Other estimates: Redfin and Realtor.com have their own. If they disagree widely, treat all of them with caution. See comparing their data.

Compare by size

When you look at comparable homes, compare the price per square foot of recent sales, then adjust for condition and features. Zillow Price/SqFt adds that figure as a badge to listing cards on Zillow, which speeds up scanning a search for outliers. See spotting homes listed below market value.

Improve your own Zestimate

If you own the home, claim it on Zillow and update its facts, such as square footage and recent upgrades. That can make the estimate more accurate, but it still won't replace a proper valuation.