Walter S. Mossberg and Katherine Boehret

A New Web Site For Real-Estate Voyeurs

If there’s anything Americans obsess over as much as sports, pop culture and college for their kids, it’s real estate. All over the country, people love to talk about how much their homes, and those of their neighbors, might be worth if sold today and what it would take to snag a new house.

Trouble is, it’s hard for average folks to obtain solid, neutral estimates of the market values of homes without consulting a real-estate agent. There have been a few Web sites that offer estimates of a home’s value, such as But they require you to enter your contact information and to be contacted by a real-estate agent or mortgage broker in order to actually receive a detailed estimate. While these sites look like they are focused on the consumer, they are actually designed to generate sales leads for agents.

Now there’s a new, well-designed, free online service for finding the value of a home that doesn’t require you to identify yourself or to communicate with an agent or broker, and provides heaps of information directly to consumers. It’s called Zillow, and it is launching today, in beta, or test, form at

Zillow uses data such as tax records, sales history and the actual prices of “comparables” — homes in your area that are similar to yours — to come up with an estimate, which it calls a “Zestimate.” It backs up the estimate with lavish data — aerial photos and maps showing prices in a neighborhood; loads of charts and graphs displaying historical data and price movements, as well as details on the size and room totals of a home. It even allows you to enter information, like the types and prices of recent renovations, that might change an estimate.

A home needn’t be for sale to be searched in Zillow, which claims to cover 62 million houses and to update its estimates daily. The company, founded by people who formerly ran the Expedia travel Web site, hopes to make money through advertising.

When estimating home values, real-estate agents can draw on their industry’s massive database, called the Multiple Listing System, as well as on their own local knowledge. Zillow doesn’t have access to the MLS or to agents’ local savvy. So, it draws on roughly 10 commercial providers of real-estate data, which supply information like a home’s sale history; tax assessment and payment history; comparable-home sale prices; and numbers of rooms in a home. This information is largely collected by the commercial-data providers from government records.

Zillow shows the estimated value of your home, and of neighboring homes, on an aerial photo, and also adds tables and graphs.
Zillow shows the estimated value of your home, and of neighboring homes, on an aerial photo, and also adds tables and graphs.

Zillow also obtains some government records directly. Zillow then crunches these numbers using its own proprietary computer formula and comes up with an estimate. The company acknowledges that its raw data on comparable sales can be three to six weeks older than the data in the MLS system that agents use.

We’ve been testing Zillow for a couple of days, and we are favorably impressed. The site is fast, broad and deep. It’s easy to use and is nicely laid out. It even offers to email updates on its estimates for any property that interests you.

However, there’s one major caveat. At least for now, while Zillow is in its beta phase, its data is spotty. For some parts of the country, Zillow has lots of good data, and it works really well. For other areas, it is still collecting and compiling figures and maps, so its results are limited or it can’t provide an estimate at all. Also, different cities and counties collect different types of information, which creates big variations in the quality of data. Zillow covers condos in multiple-unit buildings, since they’re usually listed in government records as separate homes. It has trouble with co-ops in New York City and certain similar kinds of dwellings in San Francisco.

Over time, Zillow hopes to have solid estimates for all areas. For now, though, it works best in metro areas like Seattle, San Francisco, Phoenix, Los Angeles and Cleveland. Results are weaker in metro areas like Boston, Philadelphia and Chicago. And they are weaker still in metro areas like New York, Houston and St. Louis.

For some cities, including Washington (but not its suburbs), Zillow has so little information — so far — that all it can offer is a tax assessment, not a true estimate. For some whole states, like Rhode Island, it has very few cities or counties covered. Because of these issues, Zillow can only generate estimates today for 42 million of its 62 million listed homes. For the others, it offers only basic facts.

A link on Zillow’s home page takes you to a separate page that reports on how much data and how much accuracy Zillow claims in counties all over the nation, as of that moment.

Still, when Zillow has enough data, it works great. Naturally, we checked out our own residences, both in the Washington-metro area. Katie’s residence showed little data, but for Walt’s house, Zillow had a ton of information and a “Zestimate” that seemed reasonable and accurate (once Zillow fixed a problem that initially skewed the estimates in his state). When he entered information for a remodeling job that took place last year, the estimate was even better.

Zillow also provided us with an address for one of its employees, in Seattle, and that house was also covered very well.

Each Zillow estimate starts with an aerial photo or regular street map showing the house (actually the legally defined real-estate parcel) in question, with its estimate, and neighboring parcels, with their values. You can tweak these maps and photos so they just show the “comparables” — houses most like yours.

Then, there are lots of tables listing the details of your home, or the home you’re checking; prices and details for nearby homes; taxes paid; and the sale history. You can learn how a home’s value compares with others in its ZIP Code, city, county, state or the whole country.

Graphs and charts show how a home’s value has risen or fallen in the past 30 days, one year, five years, 10 years or since its last sale. Throughout the site, Zillow provides explanations of various terms and what its data mean.

To refine a home’s value by adding new information, you use a section of the site called “My Zestimator,” which guides you step by step through the process. You can enter renovations, or just smaller changes, like new landscaping, that increase a home’s appeal. You can even choose your own comparables if you think Zillow missed them. You can also enter items here that you think detract from a home’s value, like a bad roof.

To avoid introducing bias into its system and to protect users’ privacy, these refined estimates aren’t saved by Zillow. They don’t change the estimate Zillow provides to other people looking up your home. Zillow works in Internet Explorer 6.0 on Windows, Internet Explorer 5.5 on Macintosh and in Firefox 1.5 on both Windows and Mac.

Even now, in its test phase, Zillow is a valuable online asset for homeowners or those shopping for a home. Over time, it should get even better.

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