A Zestimate is an automated estimate, and it is not an appraisal. It is a number a computer model produces from public records, listing data and nearby sales, without anyone walking through the house. An appraisal is an independent opinion of market value as of a stated date, developed by a state-licensed or certified appraiser under USPAP, with the house measured and seen. In Claremont, where one ZIP code holds several markets, most of the gap between the two is what the model cannot see.
This guide is for owners, heirs, trustees and attorneys holding a number from a website. Every article in the series is on the online estimates vs. appraisals hub.
What is an online estimate?
An online estimate is the output of an automated valuation model (AVM), a computer program that predicts a property's value from data about the property and about sales near it. The Zestimate, the Redfin Estimate and the estimators on other portals are all AVMs. None of them is an appraisal, and the portals say so in their own words.
- Redfin: "Like other estimates, the Redfin Estimate is not a formal appraisal or substitute for the in-person expertise of a real estate agent or professional appraiser." (Redfin Estimate page, accessed October 30, 2026)
- Opendoor: "Our automated valuation model uses available property data and comparable homes to estimate a value range. It does not inspect your home or collect details about its current condition." (Opendoor home value estimator, accessed October 30, 2026)
- HomeLight: "In simple terms, these estimates are only approximations, not formal appraisals." (HomeLight home value estimator, accessed October 30, 2026)
Zillow's Zestimate page refused automated retrieval on October 30, 2026, so it is not quoted here; read Zillow's wording there. The statements are set side by side in what online home value estimators say about themselves.
What does an automated estimate draw on?
- The public record, the facts the county holds about a parcel, such as lot size, recorded building area, year built and recorded sales. For a Claremont house, the assessing office is the Los Angeles County Office of the Assessor.
- Nearby sales. Redfin describes its method plainly: "The Redfin Estimate algorithm determines comparable homes by looking for nearby homes that have recently sold and have similar features."
- Listing and owner data, such as the description and photos from a past listing, and home facts an owner has edited on the portal.
Most estimators also show a confidence range, the spread of values within which the model expects the price to fall. A wide range is the model saying it has little to go on.
What is an appraisal, and who reads it?
An appraisal is an opinion of value, the conclusion about market value that a licensed or certified appraiser reaches and signs, as of an effective date, the date the opinion applies to. It is written for an intended use, what the report will be used for, and for intended users, the people entitled to rely on it: a lender, a court, a trustee, a CPA or an assessment appeals board. It is developed under the Uniform Standards of Professional Appraisal Practice (USPAP), and the appraiser is independent of every party, including the one who pays. The fee is set by the scope of the assignment and quoted before work begins, and it does not depend on the value.
The working difference is evidence. The appraiser measures gross living area, the finished, heated space above grade; records condition and quality; asks about permits; and explains every adjustment. What happens at the house is described in appraisal inspection day in Claremont.
Where does an online estimate sit among the other numbers?
Four numbers about a house are often mistaken for an appraisal.
- An automated estimate, such as a Zestimate or Redfin Estimate, is a statistical estimate from records and nearby sales. It is not an appraisal.
- An agent CMA, the comparative market analysis a licensed real estate agent prepares to suggest a list or sale price, is not an appraisal.
- A county assessment, the taxable value the assessor sets under California's assessment rules, is not an appraisal.
- A cash offer, the price a buyer will pay on stated terms, is not an appraisal.
The full comparison is on the page that sets an estimate, a CMA, an assessment, a cash offer and an appraisal side by side.
What can an online estimate not see in a Claremont house?
One ZIP code, 91711, holds pre-1940 houses near the Village and the Colleges, postwar tracts north of Foothill Boulevard, hillside homes in Claraboya and Padua Hills, and newer infill in the Village expansion. Each pocket hides something different from a model. These are the kinds of houses that come in.
Enclosed porches and old additions near the Village
Craftsman bungalows and Spanish Colonial Revival houses along Indian Hill Boulevard and College Avenue often carry decades of change: a porch closed in, a back room added, a garage converted. The public record may still show the original area, and a model can only read the record. An appraiser measures the house and asks which space was permitted. The estimate vs. appraisal for a Claremont Village bungalow works through that house type, and historic pre-1940 home appraisal describes the assignment.
A permitted ADU behind an older house
An accessory dwelling unit may not appear in the record at all, or may appear as a line with no detail. Its permit status and finish decide its contributory value, what an improvement adds to the whole property in the market. A model has no way to tell a permitted ADU from an unpermitted garage conversion.
Grade, access and view in Claraboya and Padua Hills
Hillside and custom homes in the foothills sell on view, grade and access. A steep driveway, a split-level plan or an open outlook is invisible in a parcel record, and with few similar sales nearby a model may lean on flat-lot sales below. See hillside and custom home appraisal.
Condition and quality, everywhere
No estimator has been inside the house. A kitchen redone recently and one original to the house read the same in the record. On the same street, condition and quality often separate two houses that look alike on paper.
Sales across Mills Avenue
Claremont sits at the eastern edge of Los Angeles County. Cross Claremont Boulevard or Mills Avenue and you are in Montclair or Upland, in San Bernardino County, with a different assessor and buyer pool. A model that picks sales by distance can pull a Montclair tract sale into a Claremont estimate; an appraiser uses Claremont sales first and explains any sale from across the line. What the county line does to comparable sales covers the boundary in detail.
A short sales history in the Village expansion
The newer infill west of Indian Hill, on the former citrus packing plant site, has a short sales history and belongs with its own kind. A model that blends it with the older blocks averages the difference away.
The blank comparable grid: what an estimate draws on, and what an appraisal documents
An appraisal report sets the house beside its comparable sales, closed sales of similar houses that a buyer of this house would have weighed, line by line. The grid below is blank on purpose: every figure is a dash. The second column shows what an online estimate typically has for each line.
Line in the gridWhat an online estimate usually hasSubjectComparable 1Comparable 2Comparable 3
Location and pocket
Distance on a map
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Side of the county line
Distance only, unless the model weighs it
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-
Sale date and terms
Recorded date and price
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-
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Gross living area
Recorded or listed area
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-
-
Lot size and grade
Recorded lot size; grade not observed
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-
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-
Era and style
Year built
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-
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Condition and quality
Not observed
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View
Inferred at best; not observed
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Permitted additions and ADU
Only what the record shows
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-
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Adjustments and reasoning
None shown
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The appraiser fills every row from evidence, adjusts each sale for the differences that matter to buyers here, and writes down why. That reasoning is what a lender's underwriter, a court or an appeals board reads. A model's number arrives without it.
When is an online estimate enough?
An online estimate is a reasonable starting point for curiosity. It is not enough when someone else has to rely on the number: an estate or trust needing a date-of-death value, a divorce, a property tax appeal, a lender's decision. Those readers expect an appraisal, and the estimate's own disclaimer says it is not one. Date-of-death appraisals explained plainly shows one such use.
Other questions in this series go further: is the Zestimate accurate for a Claremont house, how to judge home value estimator results, whether a no-cost home appraisal exists, and what an automated valuation model is and is not.
Next step
If you have an online number for a Claremont house and need a value someone else will read, the Claremont area page explains how its pockets behave as separate markets, and you can request an appraisal or call (909) 324-6122. The scope and the fee are settled before anything is scheduled, and the report is typically delivered three to five business days from the inspection.
Sources
- Redfin, Redfin Estimate (not a formal appraisal; how comparable homes are chosen) (accessed October 30, 2026)
- Opendoor, home value estimator (automated valuation model; does not inspect the home) (accessed October 30, 2026)
- HomeLight, home value estimator (approximations, not formal appraisals) (accessed October 30, 2026)
- Zillow, Zestimate page (attempted October 30, 2026; the page refused automated retrieval, so it is not quoted)
- The Appraisal Foundation, Uniform Standards of Professional Appraisal Practice (USPAP) (accessed October 30, 2026)
- Claremont, California (the Village expansion, Padua Hills, ZIP 91711) (accessed October 30, 2026)
- Claremont Heritage, architecture of Claremont (accessed October 30, 2026)
- Montclair, California (Mills Avenue as the western boundary) (accessed October 30, 2026)
- California Bureau of Real Estate Appraisers, license lookup (accessed October 30, 2026)
Gordon Hall, California Certified Residential Real Estate Appraiser, BREA No. AR003877 (lookup: https://www2.brea.ca.gov/breasearch/faces/party/view.xhtml?id=23601). Reports are prepared in conformity with the Uniform Standards of Professional Appraisal Practice (USPAP). Nothing here is legal or tax advice; admissibility is always the court's decision.
Frequently asked questions
Is a Zestimate an appraisal?
No. A Zestimate is an automated estimate, the output of a computer model that works from public records, listing data and nearby sales without anyone seeing the house. An appraisal is an independent opinion of market value as of a stated date, developed and signed by a state-licensed or certified appraiser under USPAP. The portals themselves state that their estimates are not appraisals.
Why is my Zestimate different from my appraisal?
Because the two start from different evidence. The model reads the public record and picks nearby sales by its own rules; the appraiser measures the house, observes condition and quality, checks permits and chooses comparable sales a buyer of that house would have weighed, then explains each adjustment. In Claremont the differences usually trace to enclosed porches and additions, ADUs, hillside grade and view, and sales drawn from across the county line.
Can I use a Zestimate for an estate, a divorce or a property tax appeal?
Those readers expect an appraisal: an opinion of value with an effective date, an intended use and intended users, prepared under USPAP. An online estimate states that it is not an appraisal, so it is a starting point at most. Your attorney or CPA decides how a value is used, and nothing here is legal or tax advice.
What does an online estimate miss most often on a Claremont house?
Condition and quality inside the house, finished space that differs from the public record (enclosed porches, back rooms and garage conversions near the Village), whether an ADU was permitted, driveway grade, access and view in Claraboya and Padua Hills, and whether a nearby sale sits across Mills Avenue in San Bernardino County.
Does an appraiser use the Zestimate in the analysis?
No. An appraisal is developed from the house itself and from closed comparable sales, adjusted and explained. An automated estimate, an agent CMA, a county assessment and a cash offer are not appraisals and are not treated as evidence of market value in the report.
