We caution buyers and sellers NOT to use Zillow's zestimate as THE resource when estimating market value/price because the zestimate doesn't factor several things that could make a difference --- for example, improvements and upgrades, expansion (that is not yet recorded), general condition of the property. It's best to work with a realtor or an appraiser who may be able to give you a closer estimate.
Zillow's own assessment is that their Zestimates are within about 10% of the market price. While that's not worst than a professional guess/appraisal, it's still a big margin of error. In the end, your best bet is to work with an agent who knows your market intimately and can at least price it to within 5% of the market price. Then, you'll just have to let the buyers bid up to the ultimate market price.
One additional tip-off: Take a look at the nature and focus of the questions posed by buyers, sellers, and owners. Here on Trulia, most deal with how to buy a property, how to sell, how to choose an agent . . . that sort of thing. On Zillow, most are complaints that their Zestimates are too low. Where there's smoke . . . .
Go to the bottom of a property page on Zillow, click on the About Zestimates button and you will see how Zillow calculates their results including accuracy ratings for specific cities. For example in NY,NY they claim that in 29.1% of the homes on Zillow their Zestimate was accurate 5% of the time.
The bottom line is it is not and should not be cosidered Gospel for home valuation.
Fran and Mark Redding
Prudential Fox Roach
1010 Stony Hill Road
Yardley PA 19067
Zillow gives estimates based on average home sales. In neighborhoods where there is a large variation of the size, type, style, and year built, zillow will be highly inaccurate. If your looking at townhouses in the same complex, it will be pretty accurate. The realtor you're working with can email you recent comparable sale with pictures so you can get a really good idea of where the banks appraisal will be. If you're not working with a realtor yet or want some free advice from one, please contact me. I live in Continental manor which is right in New Windsor as well.
Keller Williams Realty
Don't hust simply rely on any online estimates as some may be inaccurate, nor updated; rather review comps with your agent, recently sold similar properties in the immediate area, see what the data suggests and go from there.