You know that you want to sell your home. You also know that getting your listing out wherever people can see it can help you sell for the best price, right? Wrong!
Many sites are way off and one, Zillow.com, has a tool called a “Zestimate” which is supposed to give you an estimate of your home’s value. Problem is, it is very inaccurate, and it will make your home look overpriced.
“Advanced algorithm”?
Yes, the fact is that in most of these cases, the Zestimate appears to be considerably lower than the asking price. Zillow claims that when they come up with their Zestimate, they use specific types of information 
and an “advanced algorithm” to come up with a figure.
From their FAQ’s:
“We use proprietary automated valuation models that apply advanced algorithms to analyze our data to identify relationships within a specific geographic area, between this home-related data and actual sales prices. Home characteristics, such as square footage, location or the number of bathrooms, are given different weights according to their influence on home sale prices in each specific geography over a specific period of time, resulting in a set of valuation rules, or models that are applied to generate each home’s Zestimate. Specifically, some of the data we use in this algorithm include: Physical attributes: Location, lot size, square footage, number of bedrooms and bathrooms and many other details. Tax assessments: Property tax information, actual property taxes paid, exceptions to tax assessments and other information provided in the tax assessors’ records. Prior and current transactions: Actual sale prices over time of the home itself and comparable recent sales of nearby homes.”
Imperfect information
The problem comes in with where they actually get the information. For instance, some states don’t publish any information about real estate transfers, including sales price.
The physical attributes are put in by the seller, not a real estate professional. When buyers see that inaccurate Zestimate, they think that it’s the actual value and that you are overpricing your home. It makes for bad negotiating.
Trust your Realtor
Your best bet is to trust your Realtor to truthfully and expertly evaluate and value your home. Then let your Realtor choose the sites that have your listing.