How Accurate is a Zestimate?

Blog Post Image
Real Estate


For homebuyers and homeowners alike, Zestimates seem like a great way to get an estimate of a home's value. But how accurate IS a Zestimate? In this post, we'll cover what a Zestimate is, how it's created, and what you can expect from it. We'll also cover why you should always consult with a real estate professional for the most accurate information about your home's value.

What is a Zestimate?

couple discussing home with real estate agent

photo by Rodnae Productions

Zestimates are estimates of the value of homes in the U.S. based on public and user-submitted data. Zillow’s proprietary algorithm analyzes this data to automatically calculate a Zestimate, which is then updated each week with new information that affects home values — like sales, selling prices, and rents — and other factors like market conditions and demographic trends.

How accurate can a Zestimate be?

couple going over paperwork with a mortgage lender

photo by Rodnae Productions

The short answer

The short answer is: They're not very accurate. Because it's a computer algorithm that uses public data to estimate the value of a home, it's not a professional home appraisal or comparative market analysis from a real estate agent.

The long answer

The problem arises because a Zestimate may be off by many thousands of dollars when compared against an appraised home value or official tax assessment for one or more reasons:

  • The home's selling price may be different than what Zillow has recorded it for on their site.
  • There could be errors in the public record as well as some of Zillow's records (inaccurate photos or descriptions).
  • The Zestimate may not reflect improvements made since Zillow's last update.
  • Zillow includes turnover rate in their data so areas without many sales may not be accurate.

Essentially, any mistakes in square footage or omissions from tax records, public records, etc. can have an effect on the values and an error with one home could cause the Zestimates of multiple homes in that area to be affected.

Because of this, you shouldn't depend on a Zestimate to be as accurate as an appraisal. Appraisals are highly detailed and are prepared by licensed professionals who have access to your home inspection report, the interior and exterior of your house, comparable sales data from similar properties, and other information about your neighborhood.

It's also important to keep in mind that a real estate agent is not a licensed appraiser so while they can't provide you with an exact value for your home, you can expect them to give you a much better idea of what the real estate market will bear by providing you with a comparable market analysis. 

So what's the truth, can you rely on Zestimates?

realtor working with a calculator

photo by Rodnae Productions

The truth is that Zestimates are not 100% accurate. The algorithm powering the app can only take into account the publicly available data, so it doesn’t know anything about the condition of your home or its specific location, or how hot or cold your housing market is. Additionally, these estimates aren't based on an actual appraisal of your home, so they could be off by a few thousand dollars. And if you put all your faith in the Zestimate value and the appraisal comes back low - you only have yourself to blame.


Checking on a home value with a Zestimate is a great place to start, but it can't replace professional appraisers or Comparative Market Analysis. The best Zillow's Zestimates can do is to give you a general sense of what a home is worth so that you can better decide when it's time to sell or if it might be a good time to buy. And to be completely fair, even Zillow says they're only a starting point and not 100% accurate estimates. So, if you're a home buyer looking for tips on making a competitive offer, it's best to speak to a real estate agent.

It's also important to remember that the fair market value of a house can differ from its list price, which could be higher or lower than the estimated value from Zillow. You'll likely get a more accurate home value from using something like our Home Valuation Tool which draws on local MLS data to generate estimates.

There's nothing like talking to a real person to get your questions answered, either! So, get in touch with us today or leave a comment below so we can help you with your home journey!

Top real estate agents Charleston's Best Home Team  |  (843) 814-1513/ (843) 819-8570  |