The direct answer
A comparable-sales value estimate starts with relevant sale evidence, adjusts it to the subject’s characteristics, then reconciles the adjusted indications. Averaging numbers is only the arithmetic step; relevance and supported adjustments drive the quality of the estimate.
Choose evidence that competes with the subject
Review location, property type, size, condition, use and sale timing. Identify whether each observation is a closed sale, pending transaction or asking price. An apparently nearby property can serve a different market segment. Record important differences before entering values; the calculator does not retrieve listings or evaluate the reliability of a sale.
To apply the approach to an editable scenario, use the Property Value Calculator. For the neighboring question, explore Comparative Market Analysis (CMA) Calculator.
Adjust the comparable to the subject
Use supported adjustments to express what each comparable suggests for the subject. A superior comparable feature would generally require a downward adjustment to that comparable’s price when translating it to a less equipped subject, while an inferior feature calls for the opposite direction. Evidence and context matter more than a generic adjustment amount. The linked tool accepts already adjusted values.
Reconcile the indications and range
Equal weighting gives each entered comparable the same influence. Custom weighting can express relative relevance, but it cannot repair unsupported adjustments. The tool reports the weighted indication and the minimum-to-maximum entered range. That range is not a confidence interval or a certified appraisal, and a wide spread should prompt review of comparability rather than automatic selection of the highest figure.
Worked example
Adjusted indications of $480,000, $500,000 and $520,000 average $500,000 under equal weights. With weights 4, 1 and 1, the indication becomes $490,000; the entered range remains $480,000 to $520,000. Weighting changes influence, not the underlying evidence.
Common mistakes and limitations
Do not weight a comparable more heavily merely because it supports the desired value. Do not mix unadjusted and adjusted indications without identifying the difference.
User-entered comparable estimate only; not an appraisal, AVM or live-market valuation.
Frequently asked questions
Does the calculator perform an appraisal?
No. It reconciles user-entered comparable values and weights in an educational estimate.
Why does the range stay unchanged when weights change?
It is the minimum and maximum of the entered values, rather than a weighted interval.
Sources and further reading
The article’s examples are illustrative arithmetic. The references below provide context for operating, valuation or transaction concepts; they do not endorse the assumptions or the calculator.
- IRS — Instructions for Form 709 (2025) — real property valuationComparable-sales concept and adjusting for differences in date, size, condition and location.
- IRS — Publication 551 (12/2025), Basis of AssetsFair-market-value concept and use of similar-property sales as evidence.
Read our editorial policy for the scope of these educational methods.