How Accurate Is Zestimate? What Zillow's Own Numbers Say for PA Sellers

Most sellers I talk to have already looked up their Zestimate before they call me, and it usually shapes the number in their head. That is fine as a starting point, but it is worth knowing how far off that number can be, using Zillow's own published figures, before you plan a sale around it.

How accurate is the Zestimate?

According to Zillow, the Zestimate's median error rate is 1.9% for U.S. homes on the market and 7.0% for homes that are not. Zillow published those figures in its Learning Center article "How Accurate Is My Zestimate, and Can I Influence It?", dated April 13, 2022, and the page was still live when I checked it in October 2026.

Zillow also publishes accuracy statistics by region on its main Zestimate page, and it updates its model over time, so the current figures for your area may differ from the national ones above. Check Zillow's Zestimate page for the latest numbers before you rely on them.

The biggest thing to notice is the gap between on-market and off-market. If you are thinking about selling, your house is almost certainly off-market right now, which puts you in the 7.0% group.

What does a 7% median error actually mean?

A median error of 7.0% means half of off-market Zestimates land within 7% of the price the home eventually sells for, and the other half miss by more. It is a midpoint, not a maximum. Some estimates are very close, others are off by far more in either direction, and you cannot tell which group yours is in.

Worked example (hypothetical numbers). Say you own a rowhome in Point Breeze that would realistically sell for $350,000:

Even at the median, the Zestimate for an off-market home could reasonably sit anywhere in a band almost $50,000 wide. Half of homes will fall outside that band. If you list at the top of a band like that, you can sit on the market. If you list at the bottom, you can leave money on the table.

On a $600,000 house, the same 7.0% median error is $42,000 in either direction.

Why is the Zestimate more accurate for homes on the market?

The Zestimate is more accurate for listed homes because it can use listing data. Zillow says on-market data includes the listing price, description, comparable homes, and days on market. Once a home is listed, the asking price itself is a strong signal of what it will sell for, and that signal does not exist off market.

That point matters more than people think. Part of what makes the on-market number tighter is that a person, usually an agent with comps, has already set a list price. The algorithm is partly reading that human pricing decision. So the 1.9% figure does not mean the Zestimate can price your house before it is listed. For that, the 7.0% figure is the relevant one.

Why is my Zestimate wrong?

A Zestimate is usually off because the data behind it is thin, outdated, or missing what makes your house different. Zillow says it relies on public records, tax records, prior sales, nearby sales, and owner-submitted details. It cannot see condition, layout, light, noise, or the quality of a renovation, and in Philadelphia those can swing a rowhome's value a lot.

The common reasons I see a Zestimate miss on Philadelphia housing stock:

• Renovation the records do not show. A gut rehab and an original-condition house on the same block can carry similar public records and sell tens of thousands of dollars apart.
• Wrong or missing home facts. Bedroom or bathroom counts, finished basement, or square footage that never got updated.
• Unusual homes. Corner units, wider lots, parking, roof decks, or conversions that do not match the typical house on the block.
• Few recent sales nearby. Zillow says the amount of data available for your home and your area directly affects accuracy.
• Fast-changing blocks. Where new construction or recent flips are changing prices quickly, older sales data lags.

I came from the construction side, so condition is the first thing I look at. It is also the one thing an automated estimate cannot see.

Is a Zestimate the same as an appraisal or a CMA?

No. Zillow states that the Zestimate is not an appraisal and cannot be used in place of one. An appraisal is a formal valuation from a licensed appraiser, usually ordered by a lender. A comparative market analysis is a local agent's estimate built from specific closed sales, adjusted for your home's condition and features.

On the appraisal side, the rules are formal. Fannie Mae's Selling Guide requires at least three closed comparable sales in the sales comparison approach and says comps should generally have closed within the last 12 months. The CFPB says lenders must give borrowers a free copy of the appraisal on a first-lien mortgage application, promptly after completion and no later than three days before closing.

For a deeper look at how an agent prices a house, see our guide to the comparative market analysis.

How should a seller use the Zestimate?

Use the Zestimate as a rough first look, then replace it with a price built from real closed sales before you make any decision. Zillow itself encourages owners to supplement the Zestimate with other research, such as a professional appraisal or a comparative market analysis. Treat it as a conversation starter, not a list price.

Here is the order I would do it in:

1. Check your home facts on Zillow and correct anything wrong, like bed and bath counts. Zillow says owner updates can make the estimate more accurate.
2. Note the Zestimate, then set it aside. Write down the number so you can compare later.
3. Get a comparative market analysis built from closed sales on your blocks, with every address shown.
4. Compare the two and ask why they differ. If the gap is large, the answer usually comes down to condition or the specific comps.
5. Run a net sheet on the realistic price, including commission, payoff, and your share of the Philadelphia transfer tax, so you know what you actually walk away with.

My home valuation is a real comparative market analysis from Bright MLS closed sales, not an automated estimate. I send a price range with the addresses I used so you can check my work. If you are weighing a quick sale instead, I can put a cash offer next to the listing number so you see the real net of each.

The bottom line on Zestimate accuracy

Zillow's published numbers put the Zestimate's median error at 1.9% for listed homes and 7.0% for homes not on the market. Before you list, you are in the 7.0% group, and half of homes miss by more. Start with the Zestimate, then price from closed sales. The first conversation with me is about twenty minutes and costs nothing.