Evaluating Comparable Sales: How to Read Comps Like a Pro

A comp sheet can make a home look worth almost anything if the sales do not really match. The useful question is not how many addresses are on the page. It is whether those sales help explain what a buyer would pay for this property.

I’ll show you what makes a sale comparable, how to read adjustments, why an agent’s pricing analysis may differ from an appraisal, and what to check in the records. Fannie Mae’s appraisal guide gives buyers and sellers a practical set of standards for questioning the evidence. (Fannie Mae, Sales Comparison Approach)

Start with similarity, not a big list

A comparable sale, often called a comp, is a closed sale used to help estimate a subject home’s value. The sales comparison approach analyzes comparable sales, contract sales, and listings, focusing on properties most comparable to the home being valued. (Fannie Mae, Sales Comparison Approach)

For a Fannie Mae appraisal using this approach, at least three closed comparables must be reported. That is a minimum for an appraisal, not proof that every comp on the page carries equal weight. (Fannie Mae, Comparable Sales)

Compare the basics first: location, property type, size, age, condition, layout, and features that buyers in that market appear to value. A sale that is physically and locationally similar usually tells you more than a long list of loosely related homes. Fannie Mae identifies failing to use the most locationally and physically similar sales as an unacceptable appraisal practice. (Fannie Mae, Unacceptable Appraisal Practices)

More comps are not automatically better. Appraize summarizes the principle this way: “Three tight comps beat twelve loose ones.” (Appraize, How to Read a Comp Set Like an Appraiser)

Ask what makes each sale a genuine alternative for the same buyer. If the home differs in a major way, the person who selected it should explain why it still helps estimate value. A high sale price is not a reason by itself to include a property.

Check the dates and the map

Fannie Mae says, “Comparable sales that have closed within the last 12 months should be used in the appraisal; however, the best and most appropriate comparable sales may not always be the most recent sales.” A strong older sale may be more useful than a recent one that differs substantially from the subject. (Fannie Mae, Comparable Sales)

Ask where each comp is and how far it is from the subject. For Fannie Mae appraisals, distance is measured in a straight line, and the report must state the distance in miles with a direction, such as “1.75 miles NW.” A road route may be longer, but it is not the required measurement method. (Fannie Mae, Comparable Sales)

Distance alone does not settle the question. A comp across a market boundary may be less informative than one farther away that competes for the same buyers. If the sales are older or farther out, ask why they were selected and what evidence supports using them. Fannie Mae says appraisers must analyze the most comparable closed sales, contracts, and listings, with particular care when values are changing. (Fannie Mae, Sales Comparison Approach)

Statewide data can provide context, but it cannot establish the value of one house. Zillow reported an average Mississippi home value of $194,531, up 2.2% over the past year, and said homes went pending in around 36 days. Those figures describe a broad market trend, not a particular Brandon or Central Mississippi property. (Zillow, Mississippi Housing Market)

Read adjustments as evidence, not decoration

An adjustment changes the comparable’s sale price to account for a difference from the subject. If the comp has a feature the subject lacks, the adjustment generally reduces the comp’s price. If the subject has a feature the comp lacks, the adjustment generally increases the comp’s price. The comparison asks what the comp might have sold for if it were more like the subject.

Fannie Mae states, “The appraiser’s adjustments must reflect the market’s reaction (that is, market based adjustments) to the difference in the properties.” A construction estimate or rule of thumb is not enough by itself. The guide gives an example in which a $20-per-square-foot rule-of-thumb adjustment conflicts with market analysis indicating $100 per square foot. (Fannie Mae, Adjustments to Comparable Sales)

Ask what supports a large adjustment. It may come from paired sales, where similar sales with and without a feature help show the feature’s contribution, or from other market analysis. Clean pairs are not always available, so the estimate may involve judgment. Appraize cautions that “an adjustment you can’t tie to market evidence is a preference.” (Appraize, How to Read a Comp Set Like an Appraiser)

Do not reject a comp just because its adjustments look large. Fannie Mae says it has no specific limits for net or gross adjustments, and the number or amount of adjustments cannot be the sole test of whether a comp is acceptable. The important questions are whether the comp is relevant and whether its adjustments are supported. (Fannie Mae, Adjustments to Comparable Sales)

Look at the adjusted prices as a group, not just one final number. Appraize writes, “If adjusted values cluster tightly, the evidence agrees and you can trust the middle.” If they spread widely, ask what differences or weak comparisons explain the gap rather than treating a simple average as certainty. (Appraize, How to Read a Comp Set Like an Appraiser)

Look closely at concessions and changing prices

A sale price can include seller-paid costs or financing concessions. Those terms may affect what the buyer effectively paid, so the comp may need an adjustment based on the market’s reaction at the time of sale. Fannie Mae says sales with concessions must be adjusted to reflect their impact, if any, and does not allow positive adjustments for sales or financing concessions. (Fannie Mae, Adjustments to Comparable Sales)

Ask whether the reported price tells the whole story. A transaction with unusual terms may not be a clean signal of what a typical buyer would pay. The adjustment should reflect the market effect of those terms, not simply subtract the amount of a seller credit without analysis. (Fannie Mae, Adjustments to Comparable Sales)

Time adjustments need the same discipline. A sale from several months ago may need a change if market conditions shifted between its sale date and the effective date of the appraisal. Fannie Mae requires evidence to support a time adjustment or the decision not to make one, and identifies failing to make clearly indicated market-derived adjustments as unacceptable. (Fannie Mae, Adjustments to Comparable Sales; Fannie Mae, Unacceptable Appraisal Practices)

When adjusted prices do not cluster, that spread is useful information. It may mean the comps differ in important ways or the evidence is uncertain. Ask which sales deserve the most weight and why. Do not let one precise-looking average hide disagreement across the set.

Verify the sale details in Mississippi records

For each comp, ask where the sale price and property details came from. Fannie Mae says an appraisal must identify the specific data source, such as tax records or deed records, rather than using the broad label “public records.” It also requires comparable-sale data and verification sources to be reported. (Fannie Mae, Sales Comparison Approach)

That is a useful standard when you review a Mississippi comp sheet. Ask whether the reported sale price was checked against a deed record, whether the property facts came from tax records or another identified source, and whether concessions or unusual terms were verified. A record can confirm a transfer, but you still need to know what was included and whether the sale is a fair comparison.

When sale information comes from someone with a financial interest in the transaction, Fannie Mae requires the appraiser to verify it with a party who does not have that interest. The appraisal forms also require reporting the subject’s three-year sales history and the comparable sales’ 12-month history. That information can reveal a relevant prior sale or history worth asking about. (Fannie Mae, Sales Comparison Approach)

An agent’s pricing analysis and an appraisal can differ without either being a simple arithmetic error. An agent may be helping a seller choose a list strategy or helping a buyer assess an offer. An appraiser develops an opinion of value for an assignment and must analyze and report supporting sales, listings, sources, and adjustments. Ask each person what question their number answers, then compare the underlying sales and assumptions. (Fannie Mae, Sales Comparison Approach)

When something does not make sense, ask for the source and the reasoning, not just a different number. A clear explanation lets you decide whether the comp belongs in the analysis. If the explanation is missing, the comp sheet is incomplete as a tool for your decision.

Frequently asked questions

The takeaway

Pick one comp on the sheet and ask three questions: why is it similar, where was its sale information verified, and what market evidence supports each adjustment? If those answers are clear, you can judge the value conclusion more confidently. If they are not, ask for a better explanation before relying on the number.