Some people let their body weight define them. The number on the scale becomes a proxy for their self-worth, a numerical representation of their essence, their score as a human.

My self-worth is defined by my Zestimate.

Each day, I approach Zillow.com filled with hope, and fear. I don’t need to type my full address into the search bar. It auto-completes me.

Today, our Zestimate, Zillow’s estimate of our home’s value, is $5,000 more than it was 30 days ago. I smile. For the next 24 hours, I am a good person. And smart. Possibly thinner.

Zillow’s algorithm is tricky. You know how your bathroom scale is off by a few pounds when a low-pressure weather system comes through? Zillow is like that, too. Its decisions are inscrutable. One day you’re riding high; the next, the algorithm is possessed by the demons of the stock market, a low standardized test average at the local high school, the price of corn, the GDP of Finland, plunging my Zestimate inexplicably.

One day, we were down about $15,000 over the prior month and I hung my head. We were, at least that day, doomed by a cloud of insolvency slowly gathering over the top of our largest single asset.

What had we done?

Not only is Zillow my personal self-worth destruction/enhancement machine, but it’s like TikTok for adults. It’s fun to watch what other property owners are up to, or down to, depending on what the algo ate for breakfast that day. Zillow launched Zestimate in 2006. Today, it tracks the value of over 100 million homes, which means it can mess with the self-worth of over 100 million owners.

I like to check my neighbors’ Zestimates and see how their per-square-foot value compares with mine. Most of them seem accurate and nonthreatening to my Zestimate/self-worth, which is good because I like my neighbors. Then there’s the split-level across the street. The place is Nixon-era. It’s not historic, like me….I mean, like my house. It’s just old and sort of rundown and still getting a per-square-foot Zestimate similar to mine. I haven’t met the owner yet, which is probably for the best.

“ Not only is Zillow my personal self-worth destruction/enhancement machine, but it’s like TikTok for adults. ”

But maybe I should tell Zillow that my house has vinyl siding and see if that helps.

That’s the dark secret of Zillow: It turns us into liars. So what if I mess with my home’s profile settings? Zillow thinks I have 2½ bathrooms, but I only have two. Which answer gets me the highest valuation? Two and a half? Then, from now on, that will be Zillow True© (a concept I’ll copyright tomorrow). Three or four bedrooms? Three bumps it up by $1,000. Really? OK, counterintuitive to be sure but three it is. Finished basement? Ka-ching goes the Zestimate.

So be it: We own a three-bedroom, 2½-bathroom home with a finished basement—which will be news to my husband.

It’s exactly the same thing as taking off all your clothes and jewelry, waiting until you are finished with your “morning business,” removing your contact lenses and exhaling very sharply before stepping on the bathroom scale. In both cases, the only person you are fooling is yourself.

Share Your Thoughts

Do you have a love-hate relationship with your Zillow Zestimate? Let us know in the comments below.

There are lots of people like me, it turns out. Some homeowners take their Zestimate so seriously they have actually sued Zillow to ensure that they get the value that they are absolutely convinced they deserve. They, like me, are trapped in a Zestimate loop and can’t get out. Fortunately, it’s not our fault.

“It’s going back to the tribal brain we all have,” says Brad Klontz, a financial psychologist based in Boulder, Colo. “We are wired to pay extremely close attention to how everyone else values us. If you’re not paying attention to how the rest of the tribe is viewing you, you might be blindsided by a knife in the back.”

How do we keep our Zestimate from ruling our days and ruining our nights? “We really can’t,” Mr. Klontz says. “If you understand that’s just how we’re wired, it gives us the ability to transcend it.

“But for sure there’s an emotional component to it,” he says. “When do you ever get an objective number on your personal worth that updates and changes day to day?”

Well, I say, there’s the one I get from the bathroom scale.

“Ya, but unlike the scale,” Mr. Klontz says, “all your neighbors are looking at your Zestimate, too.”

Homeownerous is a new occasional column that looks at the lighter side of owning a home.

Write to Kris Frieswick at Kris.Frieswick@wsj.com