What are real estate comps?
Real estate comps — short for 'comparable sales' — are recently sold properties similar in location, size, age, and condition to a subject property, used to estimate its current market value.
A comp is only useful if it is actually comparable. The standard criteria are proximity (ideally within a half-mile, or the same subdivision), recency (sold within the past three to six months), and similarity in physical attributes: gross living area, lot size, year built, bedroom and bathroom count, and condition. The more criteria a comp satisfies, the less adjustment work is required to translate its sale price to the subject.
Appraisers, agents, and investors use comps differently. An appraiser working for a lender applies formal adjustment grids to reconcile differences between comps and the subject. An agent pricing a listing makes informal adjustments — 'this one has a pool, ours doesn't, subtract $15k.' An investor running a quick underwrite may use the median of three or four comps as a rough ARV estimate.
The reliability of comps degrades in thin markets. When fewer than three recent, genuinely comparable sales exist within a reasonable radius, the value conclusion becomes more uncertain. Rural parcels, unique properties, and highly specialized commercial assets are notoriously difficult to comp because of the thin transaction volume.
County recorder data — which Tracts sources directly — is the authoritative record of what properties sold for and when. Unlike MLS data, which is available only to licensed agents and may be removed from the database after expiration, recorded deed data is a public permanent record. For non-MLS transactions (off-market sales, foreclosure deeds, inter-family transfers), the recorder's sale history is often the only data source.