A Zestimate is our free estimated value for an individual home, which is calculated several times a week based on millions of data points. It's not an appraisal, but it does provide an approximate range for the value of your home. Zillow tries to be clear about this. Zestimate provides a general idea of the value of a home based on the information that the Zestimate model has to calculate it.
Generally, evaluators will have more accurate data to work with than Zestimate at any given time. A professional real estate appraisal is much more accurate than a Zillow Zestimate. You should keep in mind that Zestimate is just an estimate based on available data and often overlooks vital information about a home's condition and renovations. A Zestimate can't work as an appraisal and you can't use it to get a loan and you shouldn't take the value too seriously.
If you really want to understand the value of a home, you must do an appraisal. The more home sales occur in your area, the more data Zillow will have on how much buyers believe those homes are worth. Neither site is perfectly accurate for home estimates, but Zillow is generally considered to be the market leader for home estimation services. Applications such as Zillow, Waze, my Radar Detector, etc., do not use their own maps, but rather one or two common databases.
In one notable example, the co-founder of Zillow, Spencer Rascoff, sold his house for 40% less than the value of Zestimate. Presumably, Zillow won't be aware of the condition of her unit's recently renovated bathrooms and kitchens, or of the compositions. While a Zestimate is ideal for advertising when a home is on the market and is potentially a good deal, you shouldn't rely on Zillow to find out how much your home is worth. For the most part, Zillow's Zestimate seems to be more of a marketing tool to whet buyers' appetites than a tool for real estate professionals.
Zillow is a far cry from my house estimate, and it also shows a completely different location on the map. But I wouldn't consider the broad opinion on Zillow published by people who haven't considered my area of interest. I bought my house very cheaply 1.5 years ago and Zillow now estimates it at 300000 (which is what is sold in similar houses), but Red Fin (sic) still only has it for 237000 (pd 200000). However, in some cases of estimating the value of a home (especially in older neighborhoods), Zillow's estimate won't come close at all.
Its proprietary algorithm takes this information and obtains what Zillow considers to be an accurate estimate of the most likely selling price of a home. Zillow's iBuying service, Zillow Offers, can offer home sellers a quick deal on their home, in as little as 48 hours.