Why Does My Home's Value Estimate Differ From Zillow?
Because online estimates come from a formula, not an appraisal. They're built from public records and past sales, which can lag a fast-moving market, and they can't see your home's condition or recent updates. Your loan is sized on your lender's own appraisal or approved automated value, not on any website's number.
Last updated September 29, 2026What is an online home value estimate?
An automated valuation model: a computer estimate built from public records, tax data and recent sales of similar homes nearby. The sites that publish them describe them as a starting point, not an appraisal, and they can miss things like a renovation or the home's real condition. The CFPB notes it's common to see several different values during a mortgage, and an online estimate, made without anyone seeing the home, is usually the least precise.
Why can it be off, especially in a fast market?
Automated tools use sales that have already closed and been recorded. When prices are climbing, that data can trail current prices by weeks or months. The problem is real enough that Fannie Mae requires appraisers to adjust older comparable sales for changing market conditions. An online estimate may not make that adjustment, so it can come in below current value in a rising market, or above it in a falling one.
Which number does my lender use?
Its own. Whatever an online estimate or your own sense of value says, the lender sizes your loan on its appraisal or an approved automated value. That number sets your loan-to-value, which affects your rate, your down payment and whether you need mortgage insurance. Conventional loans may use a full appraisal or Fannie Mae's value acceptance, while FHA loans require an FHA appraisal.
It depends on your situation:
- Prices in your area are rising fast: expect an online estimate to trail your home's current value.
- You're refinancing or applying for a HELOC: the lender's value, not a website's, sets how much you can borrow.
- You've renovated recently: an online estimate may not reflect it; an appraiser will see it.
| Online estimate | An automated formula |
|---|---|
| Lender's appraisal or approved automated value | A licensed appraiser or lender-approved model |
Related questions
Sources
- https://www.zillow.com/learn/influencing-your-zestimate/
- https://www.consumerfinance.gov/ask-cfpb/why-did-i-receive-different-valuations-during-the-mortgage-loan-application-process-en-1875
- https://singlefamily.fanniemae.com/media/40241/display
- https://appraisalbuzz.com/understanding-fannie-maes-new-market-conditions-adjustments-policy
- https://selling-guide.fanniemae.com/sel/b4-1.4-10/value-acceptance
- https://www.fha.com/fha_article?id=4122
- https://selling-guide.fanniemae.com/sel/b2-1.2-01/loan-value-ltv-ratios
Sourced from licensed loan officers and brokers in the FreeRateUpdate network.
Educational information only, not individualized financial or legal advice. Program details and rates change; verify current terms with a licensed loan officer before making a decision.