How Are Comparable Sales Selected for a Home Appraisal?
An appraiser doesn’t pull a value out of thin air — most of the work happens in choosing which recently sold homes make a fair comparison in the first place.
The short answer
Appraisers select comparable sales, often called “comps,” based primarily on proximity, similarity, and how recently the sale closed, aiming for properties that resemble the subject home as closely as possible. Typically three or more comps are used, adjusted up or down for differences like square footage, condition, or lot size, to arrive at an estimated value. The fewer truly similar, recent sales exist nearby, the harder this selection process becomes.
Proximity comes first
Appraisers generally start by looking within a defined radius of the subject property, often the same neighborhood or a nearby area with comparable characteristics like school zones, lot sizes, or housing style. A sale two blocks away typically carries more weight than one a few miles off, since local conditions like street appeal, nearby amenities, and even specific pockets of demand can vary meaningfully within a small area. In rural or unusual markets with few nearby sales, appraisers may need to widen that radius, which can make the resulting comparison less precise and is part of why an appraisal management company’s network of local appraisers matters for coverage.
Similarity matters as much as location
- Property type and size. A single-family home is typically compared to other single-family homes of a similar square footage, not to a condo or a much larger property.
- Age and construction. Homes built around the same era, using similar materials, tend to compare more reliably than a newly built home stacked against a decades-old one.
- Condition and updates. Recent renovations or deferred maintenance both require adjustments, since two homes of the same size can differ substantially in value based on condition alone.
- Lot size and features. Extra land, a garage, or notable amenities are factored in through adjustments rather than ignored.
Recency and why it matters
Real estate markets shift, sometimes quickly, so a sale from many months ago may not reflect current conditions as accurately as a very recent one. Appraisers generally prefer the most recent closed sales available, since comparable data lagging behind a fast-moving market is one of the more common reasons a valuation can feel out of step with what buyers are currently willing to pay. When recent sales are scarce, appraisers sometimes extend the timeframe they consider, applying adjustments to account for how the market has moved since those sales closed.
Making the adjustments
Once comps are chosen, the appraiser adjusts each one’s sale price up or down to account for differences from the subject property — adding value for features the comp lacks that the subject has, and subtracting for the reverse. This adjustment process is part of what makes an appraisal a professional judgment rather than a simple average of nearby sale prices, and it’s also the part most likely to be scrutinized in a reconsideration of value request if a buyer or agent believes the adjustments were off.
The bottom line
Comparable sales selection is where much of an appraisal’s accuracy — or its limitations — actually gets decided. Understanding what appraisers are looking for in proximity, similarity, and recency makes it easier to understand why two homes that look alike on paper can still appraise differently.