Online home valuation programs and why they are usually inaccurate

The online home valuation websites are in high demand for spot checking a price. They are fast, easy, and free. 
Online home valuation graphic: same House Different ValuationsEveryone wants an easy answer, but often the easy answers aren’t all that accurate.

Online home valuation confusion

Sometimes our clients present us with “THE VALUE” of property per one of these free online home valuation websites sites and in some cases, they challenge us to disprove it (Zillow says it, or some other site, so it must be right, goes the thinking).  If they want to buy a house which is listed for more than the auto-comped value, it may cause some emotional anguish.  And if they want to buy one which is listed for less, they may feel a little giddy – unless multiple offers are looming.

The same is true with home sellers.  They agonize when Zillow, Trulia or some other big name site places a worth on their property which is less than what they feel it should be.

Often the best way to respond is to show many of the online valuations and not just the one the client is focused on (often that’s either Zillow or Redfin, but some are attached so some other site’s numbers.

What might surprise a lot of people is the huge discrepancy in values given.

Sample auto comp values online

A good exercise is picking a home that you know fairly well and then seeing what the online home valuation tools say for each one. I picked a home that I know and ran the address through several websites that provide automatic pricing info. Here are the results, from low to high:

Not included in online home valuation study:
Eppraisal $2,072,000 (too high)

Included in the online home valuation study:
Chase $1,721,800
Collateral Analytics (via Realtor.com)  $1,671,000
Redfin $1,644,906
CoreLogic (via Realtor.com) $1,631,300
NAR RPR $1,617,440 (subscription only for Realtors)
Zillow $1,580,300
Quantarium (via Realtor.com) $1,566,759
Bank of America $1,504,391

(Please note: the Trulia home value estimator is the same as Zillow’s Zestimate because Zillow owns Trulia.)

From top to bottom, the amount varies by $217,409! That’s a 14% gap between top and bottom. Had we included Eppraisal, it would have been even crazier.

How can the online home valuations disagree so much?

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