About the Comparable Sales (CMA) Calculator
This comparable sales calculator builds a simple comparative market analysis (CMA) the way agents and appraisers do: start with the sale price of each recently sold comparable home, then adjust it for every meaningful difference from the subject property. If a comp is bigger, has an extra bedroom or a better kitchen, its price is adjusted down; if it is smaller or lacks a feature your home has, it is adjusted up. The adjusted prices then point to what your home should sell for.
Enter your home’s living area, bedrooms and bathrooms, the dollar value you assign to each extra square foot, bedroom and bathroom in your market, and the details of up to four comps. Use the “other” field for differences such as condition, garage, pool, lot size, view or a price trend since the sale. The calculator shows each comp’s adjusted price, the estimated market value (average or median), the value range, and net and gross adjustment percentages so you can see which comps are the closest matches.
Adjustment values differ by market and price range — a bathroom may be worth $5,000 in one city and $25,000 in another — so base them on paired sales or local agent guidance. Homeowners can use the result to sanity-check a list price or an offer, but it is not an appraisal.
With the default inputs, the estimated market value is $369,666.67. Change any value above to recalculate instantly.
How to use the comparable sales (cma) calculator
- 1Enter your home’s living area, bedrooms and bathrooms.
- 2Set the market value of one extra square foot, bedroom and bathroom.
- 3Enter three or four recent nearby sales with their size, beds and baths.
- 4Add “other” adjustments for condition, garage, pool, lot or time since sale.
- 5Review the adjusted grid and the estimated value range.
Formula and method
Each comparable sale is adjusted toward the subject property: when the subject has more of a feature than the comp, the comp’s price is raised by the market value of the difference, and when the comp has more, its price is lowered. Size, bedroom and bathroom differences use the per-unit values you enter; the “other” field covers everything else as a net dollar amount.
The estimated value is the average (or median) of the adjusted prices. Net adjustment is the sum of adjustments with their signs as a percentage of the sale price; gross adjustment ignores signs. Appraisers commonly prefer comps whose net adjustments stay under about 15% and gross adjustments under about 25%, because smaller adjustments mean the comp is a closer match.
- P
- Comp sale price
- ΔA, ΔB, ΔT
- Subject minus comp: area, bedrooms, bathrooms
- Other
- Net $ adjustment for condition, features, location or time
Worked examples
1,800 sq ft 3-bed, 2-bath home with three comps
Comp 1 is 100 sq ft larger, so it is adjusted down $11,000 to $374,000. Comp 2 is 100 sq ft smaller with half a bath less, so it is adjusted up $14,000 to $369,000. Comp 3 has 200 sq ft, one bedroom and half a bath more, so it comes down $33,000 to $366,000. The average adjusted price is about $369,667.
Adding a fourth comp with a pool, using the median
The fourth comp sold for $420,000 but is 50 sq ft larger and has a pool worth about $25,000, so it adjusts down to $389,500. With four comps the median is the midpoint of $369,000 and $374,000, or $371,500, which keeps the higher sale from pulling the estimate up.
High-cost condo market with larger adjustment values
Comp 1 is 50 sq ft smaller (+$7,500 → $527,500). Comp 2 is 100 sq ft larger with an extra bath (−$25,000 → $520,000). Comp 3 is 100 sq ft smaller and in worse condition (+$15,000 + $10,000 → $523,000). The average is $523,500, about $374 per square foot.
Frequently asked questions
What is a CMA in real estate?+
A comparative market analysis (CMA) estimates a home’s value from the recent sale prices of similar nearby homes, adjusted for differences. Agents use it to recommend a list price or offer; it is less formal than an appraisal but uses the same approach.
How do you adjust comps?+
Always adjust the comp, not the subject. If the comp has a feature the subject lacks, subtract that feature’s market value from the comp’s price; if the comp lacks a feature the subject has, add it. The adjusted price is what the comp would have sold for if it were identical to the subject.
How much is an extra bedroom or bathroom worth?+
It varies by market and price point. Appraisers estimate it from paired sales — two otherwise similar homes that differ mainly by that feature. Local agents can usually give a realistic range for your neighborhood.
How many comps should a CMA use?+
At least three closed sales, ideally sold within the last three to six months and within about a mile (closer in dense areas). Active and pending listings can show the current trend but are not proof of value until they close.
What do net and gross adjustment percentages mean?+
Net adjustment is the total of all adjustments with their signs as a share of the comp’s price; gross adjustment adds them ignoring signs. Lower percentages mean the comp is more similar to the subject. Many appraisers aim for net under 15% and gross under 25%.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.