Online calculators are a great place to start because they're quick, easy and free. In fact, a little bit of clicking around can help you make the decision about whether or not it's a good time to sell at all. When valuing your house online, be sure the sites you use not only return a price, but also connect it accurately to your address. Also, because online estimates can vary widely, make sure you get at least five prices, nix any that seem unusually high or low, and then average the rest.
But these calculators are only a start. The data they collect is very general, including the standard things like square footage, beds and baths, and neighborhood comparables. They don't do a walk-through, so they don't know if you're next to the highway, you have an outstanding view or the condition of your house is better or worse than similar houses in the neighborhood. In other words, these estimates are just that: estimates. Once you've come up with a general idea about the price, you can move on to the next step.