Comparable Sales Calculator

Estimate home value using a Comparative Market Analysis (CMA). Enter 3 recent comparable sales, adjust for differences in bedrooms, bathrooms, age, lot size, garage, and pool, and get a weighted market value with a statistical confidence range.

Subject Property
sqft
sqft
Comparable Sale 1
$
sqft
sqft
mi
mo
Comparable Sale 2
$
sqft
sqft
mi
mo
Comparable Sale 3
$
sqft
sqft
mi
mo
Estimated Home Value
$519,792
Weighted average of 3 adjusted comparable sales | Range: $499,131 – $523,049
Weighted Avg (adjusted)
$519,792
Simple Avg (adjusted)
$511,090
Value by $/Sqft Method
$515,121
Est. $/Sqft (subject)
$263/sqft
Value Range
$499,131 – $523,049
Confidence Level
High
$
$
$
$
$
$/sqft
CompSale PriceBed AdjBath AdjYear AdjLot AdjFeat AdjTime AdjAdjusted
Comp 1$525,000——-$1,000-$400—+$1,575$525,175
Comp 2$490,000——+$2,000+$1,000—+$2,940$495,940
Comp 3$545,000-$12,000-$3,750-$5,000-$2,000-$15,000+$4,905$512,155

The confidence interval is calculated from the standard deviation of adjusted comp prices. A tight range = high confidence. A wide range = appraisers and buyers may disagree significantly.

Low Estimate (−1 std dev)
$499,131
Mean (adjusted avg)
$511,090
High Estimate (+1 std dev)
$523,049
Standard Deviation
$11,959
Lower = tighter range = more confidence
Spread (high − low)
$23,918
Confidence Level
High
2.3% std dev as % of mean
High confidence: comps are tightly clustered. The $499,131–$523,049 range gives you a reliable basis for listing price or offer decisions.

How to Use This Comparable Sales Calculator

Enter your Subject Property details — square footage, beds, baths, year built, lot size, and features. Then enter 3 recent comparable sales (comps) with their sale price, characteristics, distance from the subject property, and how many months ago they sold.

The calculator adjusts each comp for differences from the subject property (extra bedroom, newer build, larger lot, garage, pool) and outputs a weighted average estimated value. Comps are weighted by proximity, recency, and size similarity — closer, more recent, and similarly sized comps get more influence over the final estimate.

CMA Adjustment Formulas

Adjusted Price = Sale Price + Bedroom Adj + Bath Adj + Year Adj + Lot Adj + Garage Adj + Pool Adj + Time Adj
Bedroom Adj = (Subject Beds − Comp Beds) × $/Bedroom
Time Adj = Sale Price × (Monthly Appreciation % × Months Ago)
Weighted Value = Σ (Adjusted Price × Weight) / Σ Weights
Weight = (1/Distance) × (1/Months Ago) × (1/Sqft Difference)
Confidence = Low if Std Dev > 7% of Mean | Moderate: 3–7% | High: < 3%

Example CMA: 3-Bedroom Home in Suburban Market

Subject: 1,980 sqft, 3BR/2BA, built 2000, 7,000 sqft lot

Comp 1: $525,000 — 2,050 sqft, 3BR/2BA, built 2001Adjusted: $524,300
Comp 2: $490,000 — 1,850 sqft, 3BR/2BA, built 1998Adjusted: $509,400
Comp 3: $545,000 — 2,100 sqft, 4BR/2.5BA, built 2005Adjusted: $516,200
Weighted Average (by distance + recency)$518,500
Simple Average$516,600
Standard Deviation$6,100 — High confidence
Value Range$512,400 – $524,700

The tight $12,000 range across 3 well-chosen comps gives high confidence in the $518,500 estimate. Adjustments for the 4-bedroom Comp 3 and the older Comp 2 pull their prices to a consistent market value for the subject property.

Frequently Asked Questions

A Comparative Market Analysis (CMA) estimates a property's value by comparing it to recently sold similar homes in the same area. Real estate agents and appraisers adjust each comparable sale for differences from the subject property — extra bedrooms, newer construction, different lot size, and so on — to arrive at a fair market value estimate. CMAs are used for listing price decisions, offer strategy, and appraisal review.
The best comps are: (1) within 0.5 miles of the subject property (or same neighborhood), (2) sold within the last 3–6 months, (3) within 20% of the subject's square footage, (4) similar style (ranch vs. two-story), (5) similar condition (updated vs. original). The fewer and smaller the adjustments needed, the more reliable the comp. If you need to make more than 10–15% in adjustments to a comp's price, it's a weak comparable.
Appraisers use paired sales analysis — comparing two otherwise identical homes where one has the feature and one doesn't — to estimate dollar values for differences. Typical adjustments: extra bedroom $10,000–$15,000, extra full bath $7,500–$12,000, garage $15,000–$25,000, pool $10,000–$25,000 (market dependent), and $500–$2,000 per year for age differences. These are estimates — actual paired sale data from your specific market should be used when available.
Yes, in changing markets. In a market appreciating at 0.5%/month, a comp that sold 4 months ago needs a 2% upward adjustment to reflect today's prices. Lenders and appraisers typically require time adjustments when a market is clearly moving. In a flat or declining market, time adjustments may be negative. Check your local market trend data — Zillow, Redfin, or your county assessor often publish monthly price change data.
Low confidence occurs when adjusted comp prices are widely spread — for example, three comps adjusting to $480,000, $530,000, and $570,000. The standard deviation is high relative to the mean, meaning the market is variable or the comps are poor matches. In this case, try finding comps that more closely match the subject property in size, age, and location. If no better comps exist, the wide range should inform both listing strategy and offer decisions — expect appraisal uncertainty.

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