The house price estimator is based on a model NAHB has developed to estimate the average price of a home with various features in different parts of the country. By changing the age, features, location and other inputs, the model can be used to estimate how a particular amenity - for example, an extra bathroom or waterfront location - tends to impact the price of a single family detached home.

The model was developed by applying well-established statistical techniques to data from the American Housing Survey (conducted by the U.S. Census Bureau and the Department of Housing and Urban Development). The American Housing Survey contains considerable information about the units and the neighborhoods in which they're located.

The amount of geographic detail in the survey is somewhat limited, however, so the output of the price estimator is an average price for a standardized home (that is, one with a given set of features) across a broad Census region, not the price of a particular home in a specific neighborhood. House prices within a region may vary substantially. The price of a home in downtown Chicago, for example, may be quite different from an otherwise similar home in another Midwestern central city.

Also, no survey or statistical model can possibly capture all features that potentially affect house prices. Hence, there's always a chance that a particular feature in the model is acting partly as a proxy for others. If homes with fireplaces tend to have higher quality decorative hardwood trim (a feature not available in the data), for instance, the estimated impact of a fireplace could be picking up part of the effect of the hardwood trim, as well as the value of the fireplace itself.

Subject to these caveats, the house price estimator has several uses:

• Households interested in relocating or developers interested in expanding into other markets may use it to estimate the prices of a particular type of home in different parts of the country.
• Prospective buyers unsure about whether to buy a new or existing home may use it to compare prices of otherwise similar homes that are of different vintages.
• Buyers may also use it as a preliminary search tool, to get a rough idea of the cost of different size and amenity packages.
• Builders may use it to help determine if the cost of providing a particular amenity is justified.
• Developers may use it to help evaluate potential building sites, based on how site   characteristics tend to impact house prices.
• Home owners may use it to get a rough idea of how much it would cost to trade up from their existing homes to one that’s newer, larger, or has more amenities.
• Owners may also use it to judge how remodeling jobs would tend to increase the value of their homes.
• Home owners, community associations, and local governments may use it to estimate how certain public policies (such as providing public transportation, or finding a use for abandoned buildings) are likely to impact home values in their neighborhoods.

In order to access the house price estimator, you will need to have Microsoft Excel installed on your computer. You may also need to adjust Excel’s security setting in order to have the estimator run properly. In Excel, go to the Tools menu, the Macro submenu, and then click on "Security." Set security no higher than Medium. After you are finished with the estimator, you can choose to reset the security setting.