Almost every homeowner I meet has checked their Zestimate. Some are thrilled with the number, some are frustrated by it, and plenty check it more often than they'd like to admit. It's free, it's instant and it's fun to watch.
But here's the thing: an online estimate is a computer's best guess based on public data. It has never been inside your home, never walked your street and never talked to a buyer. Sometimes it's close. Sometimes it's off by tens of thousands of dollars, in either direction.
Here's why:
1. It can't see inside your home
An algorithm doesn't know that you redid the kitchen three years ago, replaced the roof or finished the basement. It also doesn't know if the bathrooms are original, the floors need refinishing or the layout feels awkward. Two homes with the same square footage on the same street can sell for very different prices because of what's inside, and the estimate treats them as nearly identical.
2. It doesn't know your street
Buyers care about things that never show up in public records: whether you're on a busy road or a quiet cul-de-sac, whether the backyard is flat and usable or a steep slope, whether there's a view, and whether the house next door is beautifully kept. An estimate sees an address and a lot size. Buyers see the whole picture.
3. It's built on data that's often wrong or outdated
Online estimates rely heavily on town records, and those records are frequently incomplete. Bedroom and bathroom counts can be off, an addition or a finished basement may never have been recorded, and square footage can differ from what's actually there. If the starting information is wrong, the estimate will be too.
4. It's looking backward
Estimates are based mostly on homes that already sold, sometimes months ago. They can't see what's happening right now: which homes are competing with yours, which ones just went under contract and how quickly, or whether buyer demand in your neighborhood is heating up or cooling off. In a changing market, that lag matters.
5. Even Zillow says so
Zillow publishes its own accuracy figures, and for homes that aren't for sale, the median error has been around 7%. On a $700,000 home, that's about $49,000, and because that's the median, half of all estimates miss by even more.
Just as important, the error isn't always in the same direction. I often hear people say, "Just knock 10% off the Zestimate." But some estimates are too high and others are too low, and there's no way to know which one yours is just by looking at it. You can't fix an estimate by adjusting it up or down a set amount.
Zillow itself says the Zestimate is not an appraisal. Check a few different websites and you'll often get a few different numbers for the same house.
I understand why people rely on them
They're easy. You don't have to call anyone, and it's interesting to see what the internet thinks your home is worth. As a rough starting point, there's nothing wrong with that.
The problem comes when that number becomes the basis for a real decision: what to list for, whether to sell at all or how much you'll have for your next home. Overprice based on a high estimate and your home can sit on the market. Underprice based on a low one and you could leave real money on the table.
Do this instead
- Get a valuation from someone who's seen your home. A local agent can account for your updates, condition, layout and lot in a way no algorithm can.
- Look at the right comparable sales. Not just the most recent sales nearby, but the ones that are truly similar to your home in size, condition, style and location.
- Look at what's happening right now. Active listings show what buyers can choose from today, and homes under contract show what buyers are willing to pay.
- Ask for a range and the reasoning behind it. A good valuation explains why your home is worth what it's worth, so you can see the logic for yourself.
- Use online estimates as a conversation starter. Bring your Zestimate to the conversation. It's a great way to talk through what the algorithm got right and what it missed.
The bottom line
Your home is worth what a buyer will pay for it in today's market, not what an algorithm calculates from public records. The only way to know that number with confidence is to have someone look at your home, your street and the current market together.
Final thought
Online estimates are a fun place to start, but a costly place to stop. If you're thinking about selling, or just curious, get a real number before you make a real decision.
Want to know what your home is actually worth? Request a free, no-obligation home valuation. I'll prepare it personally, based on recent sales, current competition and your home's features.