Are the Zillow Home Values Accurate? Tewksbury Homes

Zillow is one of the most popular real estate websites.  One of the more popular features is the Zillow Zestimate.  The Zillow Zestimate is a number that Zillow will give a home seller as a value of a house.  It will rise and fall on a weekly basis.  So the question is…. is the Zillow home values accurate?  I was prompted to write this post after reading an article, Are Zillows Las Vegas Home Values Accurate? by Debbie Drummond a Los Angeles REALTOR.

Accuracy of Zillow Home Values

Here is a case study of the past 30 homes that sold in Tewksbury MA where I could line up a Zillow Zestimate with the property.  So from an average standpoint the Zillow Zestimate was a bit off generally running to low on a properties home value.   Debbie Drummonds Las Vegas results were far more inaccurate then the results for Tewksbury MA.

  • For properties that were under priced by Zillow,  they left an average of $22,571 on the table.  While the 6.2% inaccuracy doesn’t sound like a lot, no one wants to leave $22,000 on the table.
  • So if you leave a 3% deviation plus or minus as being accurate, Zillow was accurate 6 out of 30 times leaving only a 20% accuracy.  
Address Sale Price Zestimate +/- accuracy percentage of sale
31 Rosemary Road,Tewksbury MA $273,100 $235,043 $38,057 86.06%
33 Bay Street, Tewksbury MA $392,000 $337,862 $54,138 86.19%
85 Starr Avenue, Tewksbury MA $468,000 $415,240 $52,760 88.73%
13 Kimberly Drive, Tewksbury MA $447,000 $397,291 $49,709 88.88%
45 Lowe Street, Tewksbury MA $357,500 $318,788 $38,712 89.17%
60 Melim Drive,Tewksbury MA $427,500 $384,900 $42,600 90.04%
41 Dalton Road, Tewksbury MA $379,900 $343,074 $36,826 90.31%
3 Jay Street, Tewksbury MA $320,000 $292,154 $27,846 91.30%
71 Ballard Street, Tewksbury MA $359,900 $328,821 $31,079 91.36%
87 Lincoln Street, Tewksbury MA $244,000 $223,333 $20,667 91.53%
251 N Billerica Road,Tewksbury MA $309,900 $285,438 $24,462 92.11%
110 Orchard Street, Tewksbury MA $365,000 $337,670 $27,330 92.51%
339 Trull Road, Tewksbury MA $420,000 $390,421 $29,579 92.96%
11 Munro, Tewksbury MA $267,500 $249,517 $17,983 93.28%
1441 Whipple Road, Tewksbury MA $350,000 $328,494 $21,506 93.86%
67 Secor Way, Tewksbury MA $350,000 $329,077 $20,923 94.02%
20 Easement Street, Tewksbury MA $315,000 $296,992 $18,008 94.28%
110 Greenmeadow Drive,Tewksbury MA $451,000 $425,555 $25,445 94.36%
538 North Street, Tewksbury MA $380,000 $359,881 $20,119 94.71%
11 Emily Road, Tewksbury MA $359,900 $340,892 $19,008 94.72%
7 Maplewood Road, Tewksbury MA $404,500 $383,664 $20,836 94.85%
81 Navilus,Tewksbury MA $336,900 $319,555 $17,345 94.85%
6 Amos Street, Tewksbury MA $305,000 $293,050 $11,950 96.08%
90 Hood Road,Tewksbury MA $359,900 $351,061 $8,839 97.54%
242 Mitchell G Drive,Tewksbury MA $495,000 $485,419 $9,581 98.06%
51 Melim Drive, Tewksbury MA $425,000 $419,713 $5,287 98.76%
129 Rogers Street, Tewksbury MA $233,000 $232,147 $853 99.63%
560 Whipple Road, Tewksbury MA $288,000 $289,830 -$1,830 100.64%
70 Orchard Street,Tewksbury MA $333,000 $335,771 -$2,771 100.83%
813 Chandler Road, Tewksbury MA $255,000 $264,729 -$9,729 103.82%

The Take Away of the Zillow Zestimate or the Estimated Home Value

What can we take away from the data on the Zillow Zestimate?  The Zillow Zestimate is a rough guideline.

Home Sellers- It is probably a good idea to get a rough idea of what your house may be worth when you have absolutely no idea what your current value of your home is in the current real estate market.  I think once you get serious about listing your home it is time to talk to your local REALTOR about real pricing of your home.  A comparative market analysis or CMA prepared by your local REALTOR should close that gap and give you a more accurate idea of what your home is worth.

Home Buyers- The same should hold true for home buyers as well.  If you are using the Zillow Zestimate to determine an offer it is probably not the wisest way to go, especially in a competitive market.  You would lose home after home.  Again a buyers agent could provide you with a comparative market analysis to help you determine an offer price on a home.

The Take Away? Call a LOCAL REALTOR who has a pulse on the community and general overall sense of the real estate market.

Why isn’t the Zillow Zestimate as accurate as it a Comparative Market Analysis?

The Zillow Zestimate is only using raw data from the MLS and tax records.  There data can also be quite old.  Zillow also does not have the human factor of determining the desirability of the house or the neighborhood.  Zillow can’t see the curb appeal, the function or the obsolescence of a home.  A REALTOR preparing a Comparative Market Anailysis uses raw data in combination of the latter to get a more likely selling price of your home.

I think after reviewing the data for the Tewksbury Real Estate Market, Zillow was leaving a fair amount of money on the table, that Zillow also does not take into account where the general overall market is heading.  I believe in a downturn that we would see Zillow home values overall being to high.

The last thing you must remember is the intent of Zillow.  Zillow provides consumer data to home buyers and home sellers in the hope of getting you to fill out a form or drive you to a real estate agents website.  They then sell the traffic or the lead to a real estate agent.   They are in the business of making money by controlling home buyer or home seller information to profit from agents, they do not provide you the home buyer or home seller with a service.  As long as they have massive advertising budgets to drive consumer traffic, they do not need to provide you with accurate information.


This post, Are the Zillow Home Values Accurate?  Tewksbury Homes, was provided by your local Massachusetts Realtor, Kevin Vitali.

When determining how to price your home or what to offer on a home you are considering as a purchase, it is all about understanding historical data.  I can help you understand the historical data and price your home correctly for today’s market or help you structure a winning offer.  Call me at 978-360-0422.