Why the online estimate came in higher than the appraisal

Usually because the model assumed your house was in better shape, or bigger, or more like its neighbours than it really is.

An automated estimate cannot see condition. It infers it from age and records. If the kitchen is original, the roof is near the end of its life, or an addition was never permitted, the model has no idea. The appraiser does, and adjusts for it.

Comparable sales are the other big reason. A model tends to lean on the closest recent sales. An appraiser picks sales that are actually similar, and may pass over the house next door because it was fully renovated and yours was not.

Everything that never made it into a database.

That includes finish quality, layout, deferred maintenance, water damage, the view, the traffic noise, and whether the square footage in the county file matches the tape measure. Appraisers who follow the Uniform Standards of Professional Appraisal Practice also have to support their conclusion in the report. The online model shows you a number and very little of the reasoning behind it.

No. A gap between the two is not evidence about which one is closer to the truth.

It cuts both ways. Sometimes the model is high because it cannot see problems. Sometimes an appraisal contains a real factual error, such as a missed bathroom. The online figure cannot settle that question, because it has no more information than the records do.

Yes, and that is worth remembering before treating it as a ceiling or a floor.

A thorough renovation that never showed up in public records, a finished basement, or an unusually good lot can all be invisible to a model. In those cases the appraisal may come in above the website, for exactly the same reason: one of them saw the house and one did not.

Start by reading the report itself, not the summary line.

For a first lien loan on a dwelling, federal rules require the lender to give the applicant a copy of appraisals and other written valuations developed in connection with the application. Look for factual errors: wrong room counts, wrong size, missing features, or comparable sales that are clearly not comparable. Facts can be raised with the lender. A different website number, on its own, is not a fact about your house.

If you are not borrowing and simply want a number you can rely on, the step up is to get an actual appraisal rather than an estimate.