House Comps Calculator
Estimate your home’s market value by comparing it to similar properties.
Feature Adjustment Values
Enter the dollar value for differences between your home and the comps. These are often estimates provided by real estate agents.
e.g., $150
e.g., $5,000
e.g., $3,000 (0.5 for half-bath)
Negative if older is less valuable
Your Property (Subject)
Comparable 1
Comparable 2
Comparable 3
Estimated Market Value
Based on the average of adjusted comparable sales
Comp 1 Adjusted Value
$0
Comp 2 Adjusted Value
$0
Comp 3 Adjusted Value
$0
Value Comparison Chart
What is a House Comps Calculator?
A house comps calculator is a tool used by sellers, buyers, and real estate professionals to estimate the current market value of a property. The term “comps” is short for “comparable properties,” which are recently sold homes that are similar to the subject property in location, size, condition, and features. By analyzing the sale prices of these comps and adjusting for any differences, the calculator provides a data-driven valuation. This process, also known as a Comparative Market Analysis (CMA), is fundamental to pricing a home for sale or making a competitive offer.
The House Comps Calculator Formula
The core of a house comps calculator lies in the adjustment process. You start with the sale price of a comparable property and then add or subtract value based on how its features compare to your own property (the “subject property”).
The basic formula for adjusting each comparable property is:
Adjusted Comp Price = Comp Sale Price + Σ ( (Subject Feature Value – Comp Feature Value) × Feature Adjustment Value )
The “Golden Rule of Adjustments” is simple: if the comparable property is superior to your home in some way (e.g., has an extra bedroom), you subtract the value of that feature from the comp’s sale price. If the comp is inferior (e.g., is smaller), you add value to its sale price. After calculating the adjusted price for several comps, the final estimated value is the average of these adjusted prices.
Variables Table
| Variable | Meaning | Unit | Typical Range |
|---|---|---|---|
| Comp Sale Price | The actual price a comparable property sold for. | Currency ($) | Varies by market |
| Living Area | The total habitable space of a home. | Square Feet (sq. ft.) | 500 – 10,000+ |
| Bedrooms | Number of bedrooms in the home. | Count | 1 – 8 |
| Bathrooms | Number of bathrooms (e.g., 2.5). | Count | 1 – 6 |
| Age | The age of the home in years. | Years | 0 – 100+ |
| Feature Adjustment Value | The estimated monetary worth of a single unit of a feature (e.g., value per sq. ft.). | Currency ($) | Varies greatly (e.g., $20-$200 for sq. ft.) |
Practical Examples
Example 1: Subject Property is Larger
Let’s say your home is 2,200 sq. ft. and a comparable home that sold for $500,000 is 2,000 sq. ft. The value of extra space is determined to be $150 per sq. ft.
- Inputs:
- Subject Size: 2,200 sq. ft.
- Comp Size: 2,000 sq. ft.
- Comp Sale Price: $500,000
- Adjustment Value: $150/sq. ft.
- Calculation:
- Size Difference: 2,200 – 2,000 = 200 sq. ft.
- Adjustment: 200 sq. ft. * $150/sq. ft. = +$30,000
- Adjusted Comp Price: $500,000 + $30,000 = $530,000
- Result: The smaller comp is adjusted upwards to $530,000 to be equivalent to the subject property.
Example 2: Subject Property has Fewer Bedrooms
Imagine your home has 3 bedrooms, but a comp that sold for $480,000 has 4 bedrooms. A bedroom is valued at $15,000.
- Inputs:
- Subject Bedrooms: 3
- Comp Bedrooms: 4
- Comp Sale Price: $480,000
- Adjustment Value: $15,000/bedroom
- Calculation:
- Bedroom Difference: 3 – 4 = -1 bedroom
- Adjustment: -1 * $15,000 = -$15,000
- Adjusted Comp Price: $480,000 – $15,000 = $465,000
- Result: The superior comp is adjusted downwards to $465,000 to be equivalent to the subject property. For more information, consider using a real estate valuation tool.
How to Use This House Comps Calculator
- Enter Adjustment Values: Start by inputting the estimated dollar value for key features like square footage, bedrooms, and bathrooms. These are crucial for an accurate calculation.
- Input Your Property’s Details: Fill in the fields under the “Your Property (Subject)” section with your home’s specifications.
- Add Comparable Properties: For each of the three “Comparable” sections, enter the actual sale price and features of a similar home that has recently sold nearby. You can find this data on real estate websites like Zillow or Redfin.
- Calculate and Review: Click the “Calculate Value” button. The tool will automatically perform the adjustments.
- Interpret the Results: The main result is the “Estimated Market Value,” which is the average of the adjusted prices of your comps. You can see the individual adjusted value for each comp below, giving you a clear view of how the estimate was formed. Our property value estimator can provide further insights.
Key Factors That Affect House Comps
The accuracy of a comparative market analysis depends on choosing the right comps. Here are the most critical factors to consider.
- Location: This is the most important factor. Comps should be in the same neighborhood or subdivision, ideally within a one-mile radius.
- Date of Sale: Markets change quickly. The best comps are those sold within the last 3-6 months.
- Size (Square Footage): Comparable homes should be of a similar size, typically within a 10-20% difference of the subject property’s square footage.
- Bedrooms and Bathrooms: The number of beds and baths significantly impacts value, so comps should match these as closely as possible.
- Age and Condition: A newly built or renovated home cannot be accurately compared to a much older home in need of updates without significant adjustments.
- Lot Size: The size of the land the property sits on is another important factor, especially in suburban and rural areas.
- Amenities: Features like a swimming pool, a three-car garage, or a finished basement must be accounted for when comparing properties. If you’re considering future returns, a comparative market analysis calculator is essential.
Frequently Asked Questions (FAQ)
A “comp” is a recently sold property that is similar to a subject property in terms of location, size, features, and condition. It’s used as a benchmark to determine value.
Ideally, comps should have sold within the last three months. However, using sales up to six months old is acceptable, especially in slower markets or for unique properties.
You can find recently sold property data on public real estate websites like Zillow, Redfin, and Realtor.com. A real estate agent will have access to the most accurate data through the Multiple Listing Service (MLS).
No two houses are identical. Adjustments are made to account for differences in features, size, or condition, creating a more accurate “apples-to-apples” comparison to estimate the subject property’s value.
No. This calculator provides a strong estimate for informational purposes, but it is not a substitute for a formal appraisal conducted by a licensed appraiser. An appraiser performs a much more detailed inspection and analysis. Wondering what is my house worth? An appraiser can give you the most definitive answer.
If you have a unique property or live in a rural area, it can be difficult to find good comps. In these cases, you may need to expand your search radius, go further back in time (with time-based adjustments), or consult a real estate professional.
These values are subjective and market-dependent. They are best determined by a local real estate agent who understands how buyers in your specific area value certain features. You can also derive them by analyzing paired sales data, though this is a more advanced technique.
A CMA (Comparative Market Analysis) is typically prepared by a real estate agent to establish a listing or offer price. An appraisal is a more formal, legally binding valuation performed by a licensed appraiser, usually for a mortgage lender. While both use comps, appraisals follow stricter guidelines.