Thinking about selling? Here's how to tell if your home's price has gone up or down. By the editors of Kiplinger's Personal Finance From Kiplinger's Personal Finance, October 2014 Step 1 At www.zillow.com, click on “Zestimate” and plug your address into the search box. You’ll get an estimate of your home’s market value—what you might reasonably expect a buyer to pay for it. Zillow collects data from public records and recent comparable home sales and runs the information through a computer model.See Our Slide Show: What $300K Buys You Now Step 2 Zillow says the accuracy of its data depends on what’s available in your area. Nationally, Zestimates have a median error rate of 6.9%, which means half are within the error percentage and half are less accurate. You can check error rates for top metro areas and by state in the Help Center. Also check the information for your home, such as the number of bedrooms and the total square feet of living space. Step 3 Zillow encourages users to correct the data or add features. Choose “Edit home facts and photos” from the drop-down menu next to “Report Home.” (You will have to register and sign in.) You can add a personal description of your home and upload a photo. The payoff You can get a read on whether your home’s price is going up or down. EDITOR'S NOTE: Zillow recently announced plans to acquire fellow real-estate site Trulia.com. You can also use Trulia's Home Values estimator.