How accurate are online home value estimates?
Accurate enough for a starting range, not accurate enough for a listing price. The largest portals publish their own error figures: roughly a 2% median error for homes already on the market, but around 7% for off-market homes — which is most sellers checking their value. On a $440,600 median-priced home, 7% is about $31,000 in either direction. Read any estimate as a range, never a number.
Reviewed · Reviewed by Kristian Peter, CA DRE #01308663
The gap between on-market and off-market accuracy is the part sellers rarely hear. Once a home is listed, the model can see the asking price and adjusts toward it — which flatters the accuracy statistic. Your home, unlisted, is being estimated from county records, past sales, and neighborhood comparables alone, which is exactly when the error is largest.
This is why serious estimates publish a range alongside the point number. The range is the honest part: it says the model’s confidence out loud. An estimate shown without one is marketing. Our own value lookup shows the estimate with its low and high band, plus the county record it was computed from, so you can see what the model actually knew.
The number that finally matters is the one a buyer signs. Between an algorithm and that closing, the best calibration available is several local agents independently defending their own price on your actual home — which is what sealed proposals are: each agent commits to a projected price and the comparables behind it, in writing, without seeing the others.