In real estate appraisal, an "adjustment" is a monetary value added to or subtracted from the sale price of a comparable property (a "comp") to account for differences between it and the property being appraised (the "subject property"). The goal is to determine what the comp would have sold for if it had the exact same features as the subject property. This process is fundamental to the Sales Comparison Approach, the most common method for valuing residential real estate.
This calculator helps you understand how these adjustments work by allowing you to input the features of a subject and a comparable property to see the resulting adjusted value.
Appraisal Adjustment Calculator
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How to Use the Calculator
Follow these steps to calculate the adjusted value of a comparable property:
Comparable Property Sale Price: Enter the actual price the comparable property sold for. This is your starting point.
Property Features (Subject vs. Comp): Fill in the Gross Living Area (GLA), and the number of bedrooms and bathrooms for both your property (Subject) and the one you're comparing it to (Comp).
Other Adjustments: This is a single field for all other differences. If the subject property has a feature the comp lacks (like a new roof), add a positive value. If the comp has a superior feature (like a swimming pool), add a negative value to adjust the comp's price downwards.
Adjustment Values: Enter the market-derived values for each feature difference. These values vary significantly by location and are typically determined by appraisers through paired sales analysis. The numbers provided are just examples.
Example of an Appraisal Adjustment
Let's walk through a realistic scenario to see how adjustments are applied.
Subject Property: 2,200 sq ft, 4 beds, 3 baths.
Comparable Property: Sold for $500,000. It is 2,000 sq ft, 3 beds, 2.5 baths, and has a better view valued at $10,000.
Assume the market-derived adjustment values are:
Value per sq ft: $150
Value per bedroom: $12,000
Value per full bath: $8,000 (so a half-bath is $4,000)
The calculation would be:
Base Price: $500,000
GLA Adjustment: The subject is 200 sq ft larger (2200 – 2000). So, 200 sq ft * $150/sq ft = +$30,000.
Bedroom Adjustment: The subject has one more bedroom (4 – 3). So, 1 * $12,000 = +$12,000.
Bathroom Adjustment: The subject has 0.5 more baths (3 – 2.5). So, 0.5 * $8,000 = +$4,000.
Other Adjustments (View): The comp has a better view, so we must adjust its price down to match the subject. This is a -$10,000 adjustment.
Final Adjusted Comp Value: $500,000 + $36,000 = $536,000.
This means that after adjusting for its differences, the comparable property indicates a value of $536,000 for the subject property.
Key Principles of Adjustments
Principle of Contribution: The value of an item (like a swimming pool or an extra bedroom) is not what it cost to build, but what it contributes to the property's market value. An inground pool that cost $80,000 to install may only add $30,000 in value in some markets.
Paired Sales Analysis: This is the most credible way to derive adjustment values. Appraisers find two properties that have sold that are identical in every aspect except for one feature (e.g., one has a garage, the other doesn't). The difference in their sale prices is considered the market value of that feature.
Disclaimer: This calculator is for educational and illustrative purposes only. Real estate valuation is complex and requires a licensed professional appraiser for an official opinion of value. Market-derived adjustment values can vary dramatically by neighborhood and market conditions.
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/(\d)(?=(\d{3})+(?!\d))/g, '$1,');
}
function calculateAdjustment() {
var compSalePrice = parseFloat(document.getElementById('compSalePrice').value);
var subjectGLA = parseFloat(document.getElementById('subjectGLA').value);
var compGLA = parseFloat(document.getElementById('compGLA').value);
var subjectBeds = parseFloat(document.getElementById('subjectBeds').value);
var compBeds = parseFloat(document.getElementById('compBeds').value);
var subjectBaths = parseFloat(document.getElementById('subjectBaths').value);
var compBaths = parseFloat(document.getElementById('compBaths').value);
var otherAdjustments = parseFloat(document.getElementById('otherAdjustments').value) || 0;
var valuePerSqFt = parseFloat(document.getElementById('valuePerSqFt').value);
var valuePerBed = parseFloat(document.getElementById('valuePerBed').value);
var valuePerBath = parseFloat(document.getElementById('valuePerBath').value);
var resultDiv = document.getElementById('appraisalResult');
if (isNaN(compSalePrice) || isNaN(subjectGLA) || isNaN(compGLA) || isNaN(subjectBeds) || isNaN(compBeds) || isNaN(subjectBaths) || isNaN(compBaths) || isNaN(valuePerSqFt) || isNaN(valuePerBed) || isNaN(valuePerBath)) {
resultDiv.innerHTML = 'Please fill in all required fields with valid numbers.';
return;
}
// Calculate individual adjustments
var glaDifference = subjectGLA – compGLA;
var glaAdjustment = glaDifference * valuePerSqFt;
var bedDifference = subjectBeds – compBeds;
var bedAdjustment = bedDifference * valuePerBed;
var bathDifference = subjectBaths – compBaths;
var bathAdjustment = bathDifference * valuePerBath;
// Total adjustment is the sum of all individual adjustments
var totalAdjustment = glaAdjustment + bedAdjustment + bathAdjustment + otherAdjustments;
// Adjusted comp value is the original price plus the total adjustment
var adjustedCompValue = compSalePrice + totalAdjustment;
var resultHTML = 'GLA Adjustment (' + glaDifference + ' sq ft @ ' + formatCurrency(valuePerSqFt) + '/sq ft): ' + formatCurrency(glaAdjustment) + '' +
'Bedroom Adjustment (' + bedDifference + ' beds @ ' + formatCurrency(valuePerBed) + '/bed): ' + formatCurrency(bedAdjustment) + '' +
'Bathroom Adjustment (' + bathDifference + ' baths @ ' + formatCurrency(valuePerBath) + '/bath): ' + formatCurrency(bathAdjustment) + '' +
'Other Adjustments: ' + formatCurrency(otherAdjustments) + '' +
'' +
'Total Net Adjustment: ' + formatCurrency(totalAdjustment) + '' +
'Adjusted Comparable Value: ' + formatCurrency(adjustedCompValue) + ";
resultDiv.innerHTML = resultHTML;
}