How to Read Sale Comparables Without Fooling Yourself
Comparable sales are evidence, not answers. Adjusting them honestly is most of the appraisal.
Investing · 527 words · updated 2026-08-26
A sale comparable tells you what one buyer paid one seller for one asset on one date under one set of conditions. Turning a handful of those into a value opinion requires disclosure of every way the comparable differs from the subject.
Verify the transaction first
Before adjusting anything, establish what actually happened:
- Was it arm's length? Related-party transfers, portfolio allocations, partial-interest transfers, foreclosure and deed-in-lieu conveyances, and 1031 exchange purchases under time pressure are all suspect.
- What was conveyed? Fee simple, leased fee, leasehold, or an entity interest. A leased-fee sale reflects the lease in place, not the market rent.
- What is in the price? Personal property, assumed above- or below-market debt, seller financing, earn-outs, escrowed leasing costs, and unfunded TI obligations all distort the headline number.
- When did it price? Contract date, not recording date. In a moving market a six-month gap is a different market.
The adjustment sequence
Appraisal practice applies adjustments in order, because some are multiplicative on the adjusted price:
- Property rights conveyed
- Financing terms — restate to cash-equivalent
- Conditions of sale — duress, assemblage premium, related parties
- Expenditures immediately after purchase — deferred maintenance the buyer knew it had to fund
- Market conditions — the time adjustment
- Location
- Physical characteristics — size, age, condition, quality, parking, clear height, floor plate
- Economic characteristics — occupancy, WALT, tenant credit, expense structure
- Use — zoning and highest-and-best-use differences
- Non-realty components
Quantify what you can from data — a paired-sales analysis for a location adjustment, a repeat-sales index for market conditions — and state the rest as a qualitative judgement rather than a spurious percentage.
Which unit of comparison
Price per square foot is the default for office, industrial and retail; price per unit for multifamily; price per key for hotels; price per acre or per buildable foot for land. Each has a failure mode:
- Price per SF ignores income entirely. A fully leased and a vacant building can show the same $/SF.
- Price per unit ignores unit size and mix. A portfolio of studios and one of three-bedrooms do not compare.
- Cap rate ignores everything outside year one, as discussed in the cap rate explainer.
- Price per buildable foot depends on an entitlement assumption that may not survive review.
Run at least two units of comparison. Where they disagree, the disagreement is the finding — investigate it rather than averaging it away.
Building a defensible set
- Prefer fewer, closer comparables to more, looser ones. Three well-verified sales beat twelve pulled from a radius search.
- Bracket the subject — comparables above and below on the key variables — rather than clustering on one side.
- Disclose the ones you rejected and why. An analysis that only shows supporting evidence is advocacy.
- State the confidence interval honestly. In thin markets, a value range is the correct output; a single point estimate implies precision the data cannot support.
Reconciling to a conclusion
Weight comparables by how few and how small the adjustments were, not by how close the resulting number is to what you expected. A comparable requiring a net adjustment above roughly 25%, or gross adjustments above 40%, is weak evidence regardless of how convenient it is.