function calculateUsedCarValue() {
var originalPrice = parseFloat(document.getElementById('originalPrice').value);
var carAge = parseFloat(document.getElementById('carAge').value);
var mileage = parseFloat(document.getElementById('mileage').value);
var conditionFactor = parseFloat(document.getElementById('condition').value);
var owners = parseFloat(document.getElementById('owners').value);
if (isNaN(originalPrice) || isNaN(carAge) || isNaN(mileage) || isNaN(owners)) {
alert("Please fill in all fields with valid numbers.");
return;
}
// 1. Annual Depreciation (Approx 15% per year)
var depreciatedValue = originalPrice * Math.pow(0.85, carAge);
// 2. Mileage Adjustment (Average 12,000 miles/year)
var expectedMileage = carAge * 12000;
var mileageDifference = mileage – expectedMileage;
var mileagePenalty = 0;
if (mileageDifference > 0) {
// Deduct $0.15 for every mile over average
mileagePenalty = mileageDifference * 0.15;
} else {
// Add $0.05 for every mile under average (bonus for low mileage)
mileagePenalty = mileageDifference * 0.05;
}
var valueAfterMileage = depreciatedValue – mileagePenalty;
// 3. Condition Adjustment
var valueAfterCondition = valueAfterMileage * conditionFactor;
// 4. Owner Adjustment (Deduct 3% for every owner beyond the 1st)
var ownerPenalty = 0;
if (owners > 1) {
ownerPenalty = valueAfterCondition * (owners – 1) * 0.03;
}
var finalValue = valueAfterCondition – ownerPenalty;
// Ensure value doesn't drop below scrap value (roughly 5% of MSRP)
var scrapValue = originalPrice * 0.05;
if (finalValue < scrapValue) {
finalValue = scrapValue;
}
var resultArea = document.getElementById('result-area');
var estimatedValueDiv = document.getElementById('estimatedValue');
var breakdownDiv = document.getElementById('breakdown');
estimatedValueDiv.innerText = "$" + Math.round(finalValue).toLocaleString();
breakdownDiv.innerHTML = "Valuation Details:" +
"• Age Depreciation: – " + (100 – (Math.pow(0.85, carAge) * 100)).toFixed(1) + "% from original price" +
"• Mileage Impact: " + (mileageDifference > 0 ? "Penalty for high usage" : "Bonus for low usage") + "" +
"• Condition Multiplier: " + (conditionFactor * 100) + "% of base used value" +
"• Multiple Owner Deduction: " + (owners > 1 ? "$" + Math.round(ownerPenalty).toLocaleString() : "None");
resultArea.style.display = 'block';
}
How Your Used Car's Resale Value is Calculated
Understanding the market value of a vehicle involves analyzing several depreciation factors. Unlike new cars, which lose value the moment they leave the lot, used car valuation is a nuanced process based on historical data and wear-and-tear metrics.
Primary Depreciation Factors
Our used car value calculator utilizes four critical data points to estimate what a buyer or dealer might pay for your vehicle:
Age (Time-Based Depreciation): On average, a car loses about 15% of its value every year. The steepest drop occurs in the first three years.
Mileage (Usage): The "standard" usage for a passenger vehicle is roughly 12,000 to 15,000 miles per year. Exceeding this threshold significantly lowers the mechanical lifespan of the engine and transmission, leading to price deductions.
Physical Condition: A vehicle in "Excellent" condition is rare. It must have zero mechanical issues, no paint scratches, and a pristine interior. "Good" condition is the industry standard for well-maintained cars.
Ownership History: Each additional owner increases the uncertainty of the maintenance record. Multiple transfers often result in a slight reduction in market value.
Example Valuation Scenarios
Car Type
Original Price
Age/Miles
Estimated Resale
Sedan
$30,000
3 Years / 36k miles
~$18,400
SUV
$45,000
5 Years / 80k miles
~$16,800
How to Maximize Your Car's Value
If you are planning to sell, consider these steps to boost your valuation:
Service Records: Keep every receipt. Proof of regular oil changes and belt replacements can justify a higher "Condition" rating.
Detailing: A professional deep clean and buffing of the exterior can move a car from "Fair" to "Good" condition, potentially adding 10-15% to the final price.
Address Minor Repairs: Fixing a cracked windshield or replacing bald tires often returns more value than the cost of the repair itself.