There’s nothing more exciting than getting an email from Zillow letting you know that the value of your home has increased. The site’s “Zestimate” feature, which is their version of an online home appraisal calculator, is becoming the go-to source for determining the value of a property. It typically includes previous sales of the property, similar comparable homes that have sold in the area and a trending report estimating how the property may increase or decrease over time.

In fact, the online home appraisal calculator has become so popular that many websites offer it and use it as a way to generate leads. In exchange for your estimate, you may have to provide them with your contact information or agree to be contacted by a real estate agent. Once you do, you may be inundated with emails and phone calls before you are actually ready to sell or purchase a home. 

In addition to generating countless unwanted emails and phone calls, the online home appraisal calculators have been known to provide false expectations when it comes to knowing the actual value of a property.

Here’s 3 reasons why the online calculators don’t accurately predict the real value of your home:

1. Calculators can’t see the details and the details matter a lot. Sure, computers are better calculators than most of us will ever be. However, there is value in having an estimate prepared and delivered by someone who is able to see the details, improvements and potential flaws and defects in a property. That online home estimator doesn’t know the wallpaper in the dining room is a true eyesore from the 70s. It doesn’t know if the current owner’s “kitchen renovation” was performed by a licensed contractor rather than someone who is an occasional “DIY-er” with minimal knowledge of how to install countertops properly. Real estate appraisers are able to see these details and they should be taken into consideration when calculating property value.

1. There’s no way to know what you’re being graded on. Home estimate calculators all work differently and they are all using different criteria to make their calculations. Many times, the criteria they are using for these estimates are confidential and proprietary. There’s no way to determine where the data is coming from and that’s one reason why there can be differences in property values. How do you know if the calculator is taking the fully finished and air-conditioned basement into consideration when it comes to square footage? Is it adding the pool you installed two summers ago into its calculations? With a lot of these tools, there is no way to tell – and if there is, it is difficult to alter this information.

1. Have you noticed that estimates almost never match up with other calculators?  That brings us to this point: the estimates rarely seem to line up with other online estimating calculators. Do a quick search for your home value on the top four online estimating tools and you’ll notice they aren’t the same. This leaves buyers and sellers in a difficult position. Should they go with a lower estimate and possibly leave money on the table or should they go with the higher number and make more money? While the latter is always tempting – it’s hard to know for sure and it may result in properties sitting on the market for several months because their listing prices are set too high.

Despite their flaws and inconsistencies, online home value calculators can be a good starting point when it comes to beginning your research on the value of a property.  Since they typically provide similar property sales in the area as well as information on square footage, it can be used as a rough estimate for property valuation. However, they should never be considered exact when it comes to the value of a home one is looking to purchase or sell. Only a licenced and experienced real estate appraiser will be able to determine the true value of a piece of property.