Comparable Sales (Comps)
Recently sold properties similar to a subject property in location, size, condition, and features — used to estimate market value.
Comparable sales — universally called "comps" in real estate — are recently sold properties that are similar to a subject property in key characteristics. Comps are the foundation of property valuation, used by investors, appraisers, and real estate agents to estimate what a property is worth.
What Makes a Good Comp
A strong comparable sale shares these attributes with the subject property:
Location: Within 0.25–1 mile radius. Same neighborhood or subdivision is ideal. Properties across major boundaries (highways, school districts, zoning changes) should be avoided or adjusted.
Recency: Sold within the last 90 days (preferred) to 180 days (acceptable). In fast-moving markets, older sales may not reflect current values.
Size: Within 10–20% of the subject property's square footage. A 1,400 sq ft subject should be compared to homes in the 1,200–1,600 sq ft range.
Property Type: Same type (single-family vs. condo vs. townhome) and similar configuration (bedroom/bathroom count).
Condition: Comparable level of renovation. For ARV estimation, use comps that are in the same condition the subject will be in after rehab.
How to Adjust Comps
No two properties are identical, so adjustments are made for differences. Common adjustments include: price per square foot differences for size variations, $5,000–$15,000 for an extra bedroom or bathroom, $3,000–$8,000 for a garage, $5,000–$20,000 for lot size differences, and condition adjustments for updated vs. dated finishes. For example, if a comp sold for $240,000 but has one more bathroom than your subject, you might subtract $8,000 for an adjusted value of $232,000.
How Many Comps Do You Need
Most investors and appraisers use 3–6 comparable sales. Using too few creates risk — one outlier can skew your estimate. Using too many dilutes the analysis with less-relevant data. The sweet spot is 3–5 highly relevant comps with a tight price range.
Common Mistakes
Using active listings instead of sold comps (listing prices often differ from sale prices). Selecting comps in different neighborhoods or school districts. Ignoring condition differences. Using comps that are too old in a changing market.
How Vortonic Helps
Vortonic's AI comp engine automatically identifies the most relevant comparable sales for any property address. The platform pulls from MLS sold data and public records, filters by proximity, size, property type, and sale date, and applies condition-based adjustments — delivering a curated comp set with an ARV estimate in seconds. You can also manually adjust or exclude comps to fine-tune the analysis based on your local market knowledge.
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