Why Do Home Valuations Vary So Much? An Idaho Falls Homeowner's Guide

Here's a situation I run into a lot around Idaho Falls. A homeowner looks up their house on three different websites and gets three different numbers, and sometimes they're tens of thousands of dollars apart. Then they ask me, "So which one is right?" Usually the honest answer is none of them exactly. Each one is a guess built a little differently. Once you know why the numbers disagree, you can stop worrying about the gap and figure out what your home would really sell for. If you'd like a starting point built around your own home, get a free Idaho Falls home value estimate and compare it with what you've seen online.

Every website uses its own formula

Zillow, Redfin, Realtor.com, and the banks all use their own automated valuation models. That's a fancy name for a computer program that looks at data about your house and nearby sales, then spits out a number. Every company writes its own formula, and every formula weighs things differently. One might care a lot about square footage. Another might lean harder on what sold in your ZIP code last month. Realtor.com even shows a few different estimates side by side, which tells you plenty about how much these models disagree.

None of those programs has walked through your house. They can't see your new kitchen, and they can't see the soft spot in the bathroom floor either. So the number you get really depends on which formula you happened to check.

The data going in isn't always right

These tools mostly pull from county records, listing data, and whatever homeowners type in themselves. If any of that is wrong, the estimate is wrong too. I've seen county records list the wrong number of bedrooms, a basement that was finished years ago still marked as unfinished, and square footage that didn't match the house at all.

One site might have caught a correction while another hasn't. That alone can push two estimates far apart. If you only do one thing after reading this, look up your home on the county assessor's site and make sure the basics are right.

Idaho keeps sale prices private

This is a big one here. Idaho is a non-disclosure state, which means sold prices don't have to be made public the way they are in a lot of other states. The websites can't always see what nearby homes actually sold for, so some of them fill in the gaps with list prices, older sales, or their own guesses.

That's one reason estimates in Eastern Idaho can bounce around more than you'd expect. The tools are working with less real information, and each company fills in those blanks its own way. I went deeper on this in my post on how accurate online home value tools really are.

Unusual homes and rural property throw them off

Online estimates do best in neighborhoods where the houses are pretty similar and sell often. A newer subdivision in Ammon with lots of look-alike homes is easier for a computer to price than a one-of-a-kind house out by Rigby on a couple of acres, or a place near Ucon with a big shop and outbuildings.

When there aren't many true comparisons nearby, each model reaches farther out or uses whatever it can find. One might compare you to a house in town. Another might compare you to a farm property miles away. Neither one is really your home, and that's where the big gaps come from.

Timing and updates

Some sites update their numbers more often than others. If the market has shifted in the last few months, one estimate might already reflect it while another is still running on older sales. Listed homes also tend to get more accurate estimates than homes that aren't for sale, because the tools suddenly have photos, a description, and a list price to work with. That helps once you're selling, but not much while you're still deciding.

So which number should you trust?

I'd treat the online numbers as a rough range, not an answer. If your estimates are spread far apart, that's the tool telling you it isn't sure, not proof that one site has it right. You can learn more about why one site in particular tends to run low in my post on why Zillow says your home is worth less.

When you're getting close to a real decision, you want a value built from actual closed sales of homes like yours, adjusted for condition and upgrades. That's what a good market analysis does, and it's what an appraiser does too. A person who knows the area can tell you that the house down the street sold higher because it had a new roof and a finished basement, not because the neighborhood suddenly jumped.

How I can help

I've lived in Eastern Idaho for about 15 years, and I started Smart Seller to help people and give sellers options that fit their situation. When you're ready to sell, my Smart Seller listing programs let you pick how much help you want, and you can cancel anytime. You can read more about me or see the towns I serve on my Idaho Falls real estate page.

If the online numbers have you scratching your head, request your free home value estimate and I'll walk you through what's behind it, no pressure. Or email me at alan@smartselleridaho.com. - Uncle Al

Idaho Falls Home Seller FAQs

Why is my home value different on every website?

Each site runs its own formula with its own data, and none of them has seen the inside of your house. Small differences in what they know about your home and which sales they compare it to can add up to a big gap.

Which home value website is the most accurate?

It depends on your house and your area, so no single site wins everywhere. In Eastern Idaho, where sale prices aren't public, I'd use them as a ballpark and lean on real closed sales for anything important.

Why is my appraisal different from Zillow?

An appraiser walks through your home and picks sales a buyer would actually compare it to, then adjusts for condition and features. Zillow works from records and formulas, so a gap between the two is pretty normal.

Can I fix the information the websites have about my home?

Often, yes. Start with your county assessor record, since many sites pull from it, and some sites like Zillow let owners update their home's details.

What's the best way to get a real number for my home?

Ask for a market analysis based on recent closed sales of homes like yours, or hire an appraiser if you need a formal value. A free home value estimate is an easy first step, whether you're in Idaho Falls, Rigby, Ucon, or nearby.

Photo: The Museum of Idaho in downtown Idaho Falls, Idaho, by Jcarr29 / Wikimedia Commons, CC BY-SA 4.0