How much is it worth? That's the question many homeowners want answered in the summer selling season, when buyers scramble to complete their purchase before rates take a big leap.

Whether you are serious about buying or selling or merely curious about your home's value, you've probably wondered about how to come up with a reasonable estimate of value.

The definition of fair market value is the price that a typical buyer might be willing to pay and that you might be willing to accept, given normal motivation to complete the transaction and given full knowledge of the marketplace.

That means a seller who is neither distressed nor pressured to sell. And it means a buyer who wants to buy but doesn't have to -- and is willing to pay only a fair price for the property.

The last part of the definition is a recognition that "fair market value" is based on the market conditions as they exist at a specific time. If interest rates change or competition increases or if we find out that bricks cause cancer, there could be an impact on the value of your home.

Appraisers use three methods to help estimate value. The first two are much less indicative of the behavior of the average buyer than the final one, so that is where we will spend our time. That approach is called the comparable sale method.

The underlying assumption is that if you can find three or more homes that are relatively near your home and are similar in age, size, style and condition, you can predict approximately what your home might be worth.

This procedure works well in a subdivision of relatively new homes, especially if most of them are similar in construction and age. Unfortunately, it breaks down in neighborhoods with a wide variety of homes. It's also hard to tell in an area where there hasn't been much recent sales activity.

If you want to look up information about recent home sales, try these:

• Free Web sites -- such as ajc.com and domania.com -- offer limited information in exchange for a simple site registration. You can get a street address and a selling date and price. Sometimes you'll also find the number of bedrooms and bathrooms plus the county tax assessment. But often the information is more than 6 months old.

Such information is helpful as a starting point but too scanty to give you more than a general idea of price movement in an area. It's mainly an easy way to start your investigation.

•  County tax records listing sold property are available on a paid subscription basis. It's too costly for homeowners just wanting a casual listing of recent sales.

•  Multiple listing services provide their agent members access to two data areas. The first is the above mentioned county tax records, which are sorted and easy to use. You can search according to almost any parameter, including ZIP code, street or neighborhood, date and sales price. This is public information that has been purchased from the counties.

The second is the listing and sales data gathered by the agents themselves as they list and sell homes through their respective brokerage firms. As you might expect, the data are extremely detailed and accurate, and perhaps more importantly, are current as of yesterday.

This information is available only to agents whose brokers are members of the particular listing service involved.

•  Licensed appraisers have access to the information listed above as well as their own records of previous appraisals.

But it is not wise to pay for an appraisal you may not need. And because none of the most accurate sources of information is free, what's the best way to estimate your home's value? I recommend making friends with a real estate professional.

Because agents need to keep a mental inventory of homes for sale and have gone inside many homes in your area, they can give you an insider's opinion on what your house might be worth.

Even if you explain you're not planning to sell but simply want to review recent sales to stay abreast of values, you'll usually find an agent willing to share their knowledge.

The best agents get most of their business by referral. So agents and homeowners can both benefit.

 John Adams is a broker and investor. His Web site is www.money99.com.