How Accurate Is Zillow's Zestimate in Texas?

Almost every seller I meet has already looked. That's reasonable — the number is free, instant, and sitting on the internet with your address attached to it. The trouble starts when it becomes the anchor for a pricing decision, because in Texas that number is built on a foundation with a piece missing.

This isn't a complaint about Zillow. Their model is genuinely sophisticated, and Zillow publishes its own error rates, which is more transparency than most estimators offer. The problem is specific to where we live.

Why Texas breaks the model

An automated valuation model does essentially what an appraiser does, at scale: find comparable homes, see what they sold for, adjust for differences. Everything depends on that middle step.

In Texas, what homes sold for is not public information. Texas is one of a small number of non-disclosure states. When a home changes hands here, the deed is recorded — but the price isn't. Governmental entities, including county appraisal districts, cannot compel a buyer or seller to disclose the sale price.

So a national model pointed at a home in Rockwall, Rowlett, Garland, or anywhere else in DFW is working without the single most important input. What it has instead:

The people who do have sold prices are licensed agents. Sold data is reported to the MLS by the listing broker under MLS rules, which is how a local agent can see what actually closed on your street last month while a national model can only infer it. That gap is not about skill or effort — it's about access to a dataset that doesn't exist publicly in this state.

What the error rate actually means for your house

Zillow publishes its accuracy figures, and they're worth reading carefully because two numbers get quoted interchangeably when they describe very different things.

Off-market homes — homes not currently listed, which includes yours right now — carry a nationwide median error of roughly 7% in Zillow's published data. On-market homes come in far tighter, in the low single digits.

That gap looks like the model getting smarter when a home lists. It isn't, entirely. Once a home is listed, the model can see the list price, and the estimate moves toward it. An on-market Zestimate is partly a reflection of a number a human being chose. Which means the impressive figure is the one that describes homes where the answer was already visible, and the weaker figure is the one that describes your situation when you're deciding what to ask.

Then there's the word median, which does a great deal of quiet work. A median error of 7% means half of all homes are off by less than 7% — and half are off by more. It is not a margin of error or a worst case. It's the middle of the distribution, and the tail on the wrong side of it is long.

On a $450,000 home, 7% is about $31,500. For half of homes, the miss is larger than that. Set an asking price off by $31,500 in the wrong direction and you've either left real money behind or bought yourself the slow, expensive version of selling — homes in this market that had to cut their price sold for 90.7% of original ask and took 97 days, against 98.7% in 18 days for homes that never reduced.

Accuracy also degrades in exactly the places DFW is full of. Models do worst where sales are thin or homes are unlike their neighbors: acreage in Lucas, waterfront on Lake Ray Hubbard, custom homes in Heath, a 1978 house on a street that's been half rebuilt. Anywhere the comps are scarce or the subject is unusual, the number gets softer — which is the opposite of what most sellers assume.

What to use instead, and what each thing is actually for

Three different numbers get treated as interchangeable. They aren't, and knowing which question each one answers is most of the battle.

One more worth separating out: your appraisal district value is not a market value and was never meant to be. It's the basis for your tax bill, subject to statutory caps, and it can sit well below what a home would sell for. If yours seems high relative to what your house would actually bring, that's a protest conversation, not a pricing one.

The practical move is simple: use the automated estimate as a starting point, then get the sold comps before you decide anything. The gap between the two is frequently large, and in a non-disclosure state it is large in ways no national model can see.

General information for North Texas homeowners, not an appraisal or a valuation of any specific property. Accuracy figures referenced are published by Zillow and are updated periodically — check their current accuracy disclosures for the latest. Zillow and Zestimate are trademarks of Zillow, Inc.; The Dunnican Team is not affiliated with Zillow. Market figures cited are from an analysis of 2,999 closed NTREIS sales in Rockwall County and Rowlett for the twelve months ending September 11, 2026.