How Zillows Estimates Work

Zillow acquires data from tax assessor and county records, real estate brokerages, and multiple listing services (MLS). It also incorporates user-submitted data. For example, a homeowner may contact Zillow to update information about their property’s features. The owner may improve the Zestimate accuracy for their home by submitting up-to-date information on finished square footage, number of bedrooms and bathrooms, and lot size.

How accurate are Redfin home estimates?

The “Redfin Estimate” is the site’s calculation of a home’s market value. Redfin, which updates its numbers daily for on-market homes, claims that it has “the most accurate online home-value estimate.”

The site uses the following data to determine home values:

  • Full access to multiple listing services (MLSs)
  • Comps on recently sold homes
  • Special features

The median error rate of the Redfin Estimate is 1.77% for homes on the market, the company says. Here’s what Redfin has to say about that:

“This means that when a home that is currently on the market sells, the Redfin Estimate will be within 1.77% of the sales price half of the time.”


How We Chose the Best Home Value Estimator Sites

We evaluated dozens of free home value estimator sites. We paid particular attention to those associated with an established online real estate brand. Although no home estimator site is 100 percent accurate, we chose the most accurate ones that returned low median error rates. For those that did not have a median error rate, we compared the estimates for their market and off-market homes to the results of our top two choices. We also preferred home value estimator sites that offered other valuable tools to customers in the home buying and selling processes.

How Redfin Estimates and Zillow Zestimates work

Like other similar tools, Redfin and Zillow calculate a home’s estimated value using publicly available data, like tax records, recent property sales, and local market trends.

The estimator considers all of that information and uses it to approximate the value of features of your home. The more data an estimator has about your property and similar homes in your area, the more accurate the estimate is.

For example, if a home sold in the past few years, the property facts from the old MLS listing are likely still accurate. On the other hand, if the property has been off the market for a while, Zillow and Redfin may not be aware of home modifications the owner has made over the years.

Also, Zillow and Redfin’s estimators don’t have access to essential information about your home. Details such as interior layout, the state of your roof and HVAC systems, and your home’s curb appeal don’t appear in public data sets, so they won’t factor into your estimate.

For a complete analysis of your home’s value, you need to have your property evaluated by a real estate professional. They can assess the factors Zillow and Redfin miss, allowing them to calculate what your home is worth more accurately. 

Why do Redfin and Zillow have different estimates for my house?

Most of the time, Zillow and Redfin have different estimates for your house because they have slightly different approaches to calculating home values. However, if there is a huge gap between your Zestimate and Redfin Estimate, it may mean that one company has inaccurate information about your home.

Redfin and Zillow both rely on public, MLS, and user-submitted data to estimate the value of your property. Although they operate similarly, they may be using different information to calculate their estimates. For example, one estimator might not include traffic data in your area, while the other one slightly penalizes properties in high traffic areas.

Since Redfin and Zillow don’t tell us exactly how their tools work, we don’t know the specific differences between how they estimate home values. 

Is a Redfin Estimate or Zestimate the same as an appraisal or a CMA?

No. A formal appraisal or a comparative market analysis (CMA) involves a real estate professional actually examining your property, while an online estimator just uses public data sets to make assumptions about your home. This is why online estimators are just a starting point for evaluating your property.

When an appraiser or real estate agent evaluates your home, they’ll visit it personally to gather accurate information on your property’s attributes, including features that may not appear in tax records or old MLS listings. 

For example, while Zillow and Redfin can likely find basic facts like your home’s square footage and number of bedrooms, they won’t know much, if anything, about your home’s condition. When you get a CMA or appraisal, the estimate will also account for critical factors like the age of your heating and cooling system, the amount of traffic in your neighborhood, and the quality of interior modifications like a refinished kitchen. This helps the agent or appraiser produce a highly accurate assessment of your property’s value.

How to fix an incorrect Redfin or Zillow estimate

If you believe your Redfin Estimate or Zillow Zestimate is inaccurate, both sites allow you to edit your home facts. When an estimate is based on inaccurate or outdated information, updating your property information typically improves the estimate’s accuracy.

For example, on Redfin, just visit the page of your property and click on the “Edit Home Facts” link, as shown here:

Be aware that this process involves proving that you are the property owner. This means giving your contact information to those companies, who may use it for advertising purposes. 

Should I update my property information on Redfin and Zillow before selling?

If updating your property information on Redfin and Zillow could help the sale of your home, then it’s worth considering. 

For example, if an estimator has incorrect data about your home that would cause a lower estimate, a buyer who sees that estimate may want to make a lower offer on your home. If Zillow is calculating your estimate based on two bedrooms when your home actually has three, then correcting that data should raise your Zestimate — and give buyers a better idea of what your home is really worth.

On the other hand, if the current estimate is accurate or even higher than you expect, you should talk to your agent before editing your home facts. They can tell you whether it’s worth updating your property information anyway or the home facts are fine as-is.

Why Zillow And Redfin Are Sometimes So Off With Their Pricing Estimates

Zillow and Redfin’s pricing estimates can be very off for the following reasons:

  • Zillow and Redfin often have incomplete data about your property
  • Savvy homeowners are not updating their property’s features after a remodel to keep the property tax assessor’s office at bay
  • Their algorithms can’t update quickly enough in a rapidly declining or rising market
  • Zillow and Redfin have entered into the business of buying and selling homes (iBuying aka instant buying)

Let’s first talk about the last point and why it’s hard to fully trust Zillow and Redfin’s pricing estimates.

The Advantages of Using One of the Best Home Value Estimator Sites

Home value estimator sites will never be 100 percent accurate. This is because these sites each use various methods to compile their values. But just because they aren’t 100 percent accurate doesn’t mean that they aren’t helpful. For instance, a user may want to know the value of their home before attempting to refinance or sell it without having an appraiser assess it. Appraisals can be very costly, running upward of thousands of dollars depending on the property’s size. So before putting money down, it would be a good idea to see how much the home is worth. Home value estimator sites give a user a ballpark average of a home’s value.

  • The estimate is immediate.
  • A home value estimator is a free tool.
  • Since a home value estimate is free, users can get several estimates and compare them.

Redfin vs. Zillow: Estimating Home Value

Both companies have tools on their websites that provide an estimate of your home’s values. Since they each use their own proprietary technology, don’t be surprised if the results are off by hundreds or even thousands of dollars. 

Redfin Estimate

Redfin uses MLS data on recently sold homes in your area to come up with a Redfin Estimate. 

According to their website, a Redfin Estimate is the most accurate of the online estimating tools. Their study of 5,000 homes shows that 64% of them sold for within 3% of the estimated value. By comparison, that same Redfin study showed that only 29% of homes fell within 3% of Zillow’s Zestimate. 


Zillow’s Zestimate is one of the most popular features on its website. It uses a proprietary algorithm to calculate the value of your home that includes both public data and user data. 

According to Zillow’s own website, their median error rate for homes on the market is 1.9%. For off-market homes, since less data is usually available, the median error rate is 7.5%. 

Zillow vs. Redfin: Clarks view

That disparity is something that money expert Clark Howard discussed in a recent podcast, where he said that consumers should do a head-to-head with Zillow and Redfin.

“If you live in a very high-end home — no chance,” he says, referring to how the sites probably won’t give you similar estimates. “But for the great middle of the market, which involves probably three-quarters of homes in the country, these things can be a useful tool.”

To illustrate Clark’s point, we compared a more modest home for sale in Marietta, Georgia, a suburb of Atlanta.

The home is listed for $245,000.

The Zillow estimate of this Georgia home is:

The Zillow estimate of this Georgia home is:

$184,948 (Zestimate range: $176,000 – $205,000)

Home features listed: 5 beds 2 baths 1,750 square feet.


Redfin Estimate vs. Zillow Zestimate

The Redfin Estimate and Zillow Zestimate are two competing home value estimation tools. Since they will sometimes give two different numbers for the same property, not surprisingly, users are curious as to which tool is more accurate. 

Is the Redfin estimate or Zillow Zestimate more accurate? As we’ve covered in Can the Zillow Zestimate be Trusted?, Zillow has a median error rate of 1.9% for on-market homes and 7.5% for off-market homes. So according to these self-reported numbers, Zillow’s Zestimate tool tends to be more accurate for both, when compared to Redfin’s (3.02% for on-market and 8.69% for off market).

So many factors impact the estimates, though, that sometimes Redfin will be more accurate, and sometimes Zillow will be more accurate.

One way Redfin pulls ahead is with transparency. Zillow offers very little information apart from the Zestimate number itself. Redfin, however, automatically pulls up the properties it’s comparing your property to, as well as a map of where they’re located. This makes it a lot easier to understand whether Redfin is accurately accounting for the features and updates (or lack thereof) your home has.

Off-Market Comparison

Here’s an example of how different the estimates can appear for the same off-market house located in Philadelphia’s popular Bella Vista neighborhood.

  • Zestimate: $295,300
  • Redfin estimate: $353,794

As you can see, there is a range of over $50,000.

Using Redfin to look at recently sold properties, for roughly comparable homes (under 1,000 square feet, 2 bedrooms), the very lowest a home in this neighborhood sold for in the last 3 months for was $296,000 – with an average selling price of $354,300. However, these homes still averaged 915 sq. ft ($387/foot) – whereas this is a 756 sq. foot home. 

While at first, it seems like the Redfin estimate is more accurate based on what’s sold recently – if we take square footage into account and assume each square foot is worth roughly $387, then based on this information alone, the Zestimate seems closer to what the actual sale price would be.

 The actual selling price, though, may differ yet again if the home is either extremely dated or has recent updates when compared to recent homes sold in the area.

On-Market Comparison

Here’s an example of a current on-market home located in Philadelphia’s hot Northern Liberties neighborhood.

  • Listed Price: $599,000
  • Zillow Zestimate: $598,700
  • Redfin Estimate: $587,527

In this example, both estimates are a lot closer to the listed price, likely because the sites had more property information to work with. However, there is still a difference of over $10,000 between the two estimates.

How Appraisers Assess Value

Before the lender will sign off on your home loan, they will insist on a home appraisal. Typically, this costs several hundred dollars and is paid for by the buyer.

Home appraisers must be licensed and certified by the state. Their job is to conduct an unbiased assessment of the home's value. To do this, they'll conduct a walk-through, comparing the house's features against a checklist. They'll look for visible defects, but they won't look for potential issues in the same way as a home inspector would.

Appraisers usually issue a written appraisal report, including photos of the property, a street map, information about comparable properties, and market data.

Who Would Sell To Zillow and Redfin?

Now that we understand Zillow and Redfin are our competitors, who would want to sell to them? People who either don’t know better, don’t want top dollar, or want an easy sale. This is fine if that’s what you want. But, if you’re selling to Zillow or Redfin without all the facts, this is a suboptimal financial move.

Pitching peace of mind is a smart way to get platform users to sell their homes to Zillow or Redfin. Selling a home can be very stressful, as I found out back in 2017. Even though it took a reasonable 45 days to sell my home, I was still very frustrated with the process.

[Thankfully, not too many people are selling to iB
[Thankfully, not too many people are selling to iBuyers]

To expedite a sale, Zillow will offer a guaranteed purchase price (below market) so you don’t have to go through the anxiety of selling your home. Selling a home takes work. You may want to hire an agent, stage your home, market your home, negotiate with a buyer, and wait for the contract to close.

Contracts can sometimes fall through. Zillow and Redfin cut out the middle-people and provide greater assurance your home will get sold. That said, you still don’t know for sure whether Zillow or Redfin will go through with their offer until the money is in your bank.

In a strong real estate market, it is better to test the open market to potentially create a bidding war rather than sell directly to Zillow and Redfin. You can first test the waters with a “pocket listing” that internally markets your listing within a brokerage. Then you can open it up to the MLS. Or, you can try and sell the property yourself.

In a weak real estate market, selling directly to Zillow or Redfin may make more sense if you are presented with an acceptable price offer. Contracts in a weak real estate market tend to be more at risk of falling through. However, Zillow and Redfin aren’t stupid. In a weak real estate market, they will offer you an even lower low-ball price.

I suggest first trying the traditional way of selling your home first. If that fails, then you can consider selling to Zillow, Redfin, Opendoor or other iBuying firms.

Can You Dispute the Redfin Estimate?

Many homeowners worry that a too-low Redfin estimate can negatively impact them when they go to sell their home. A consumer who believes that a home is worth $400,000 is going to feel like they’re overpaying at $450,000 – even if that’s the true market value.

Unfortunately, it’s difficult to dispute the Estimate for Redfin homes for sale – a similar lawsuit was brought by homeowners against the Zillow Zestimate, and the court sided with Zillow. In other words, Redfin is not doing anything illegal by posting an estimate of your home – so long as they clearly indicate it is not an “appraisal.”

What you can do as a homeowner is update the listing information yourself so that Redfin has more accurate data to work from. Note: this is only allowed for non-active and sold homes. If your home is currently for sale, you’ll need to contact your listing agent to have the MLS information updated.

 Redfin allows you to update your listing with:

  • Any renovation projects you’ve done (you can specify the total cost, project type, and more)
  • Property info (parking spaces, year built, square footage, etc)
  • Property features (basement, waterfront, accessible, etc)
  • The location (if it was incorrect)

Frequently Asked Questions

Is Zillow better than Redfin? 

It depends on the reason why you’re using their services. As a discount brokerage, Redfin can save you money. But if you want to sell FSBO, only Zillow will take your listing. 

Does Redfin really save money?

Yes, if you are selling your home. Redfin’s services start at 1.5%, compared to the typical real estate commission of 2.5% to 3%. 

Which home value site is most accurate? According to their studies, Redfin is more accurate. This might be due to their consistent updates, occurring multiple times throughout the day and keeping data fresh. 


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