"What's my home worth?"

It's one of the most earnestly asked questions out there. I mean, what homeowner WOULDN'T want to know the precise value of their biggest asset?

And the internet -- along with every Realtor, lender, appraiser, investor, neighbor, and father-in-law in the universe-- is all too happy to throw out a number!

You've undoubtedly heard about (and played with) one or many of the "AVM" tools (Automatic Valuation Model.)

These mega-websites each have their own unique software algorithm that pulls data from hundreds or thousands of different sources, including tax records, sales history, economic growth indicators, market absorption rates and countless other macro and micro-influencers. Then they spit out a number.How do they compare to each other? Let's do a showdown and find out.For this experiment, I'll use a rental house we own: 31 Valley Crest Way in Sudden Valley. I'm going to plug that address into the four valuation tools below, and show you the price they deliver:

Zillow -- the 800 lbs. gorilla of online valuations -- spit out a price of $296,413.

Redfin has a valuation tool as well. Redfin gave the house a price of $286,066.

Realtor.com offered up a value of $296,500.

Chase.com rounded out the valuation showdown with an even $286,000.

The numbers are relatively closely grouped within about a 3.5% range of each other.

In this case, somewhat coincidentally, I would say these numbers are very, very close to market value. If I were selling the home (I'm not, because it's currently rented) I would prep it and price it at about $295K. I would expect a sale within 3 weeks at that price.

But I say "coincidentally" because the auto-values can be way, WAY off from one another -- and way off true market value.

In our batch of 24 homes we're selling for the Bellingham Housing Authority, we tracked Zillow and Redfin values before we listed them. The homes had also been professionally appraised, and we had conducted a "Comparative Market Analysis" on each one -- all prior to listing or looking at offers.

The group of case studies is the subject of its own blog post to dive deep into the comparisons and to see which one proved most accurate. But here's one random example:

We knew we'd be selling a house on Cedar Hills Rd.

The appraiser valued it at $350,000.Zillow valued it at $424,127 before it was listed.

Redfin valued it at $354,027 before it was listed.

We listed it at $350,000 and expected multiple offers.

Once it was listed, Zillow's value dropped to $386,900.Redfin's value, once it was listed, climbed to $425,689.We got 6 competing offers, and it ultimately closed for $380,000.So... the algorithms were hard at work, re-calculating as they get new data... trying to get close to true, fair market value.

At the end of the day, the ultimate "valuation tool" is to hit the market, well-optimized, with a listing process that won't leave money on the table, won't stay active so long it cools off, has representation by an established, experienced Realtor with a good reputation, is easy to access with short notice, and delivers on the sensory experience spectrum for the buyer.

THAT is the surest way to find a home's true value.PS... Less than 4 months after the sale closed, the house on Cedar Hills is valued as follows by the big sites:

Zillow: $385,909Redfin: $425,689Realtor: $385,900

Chase: $397,000