function calculateLease() {
var msrp = parseFloat(document.getElementById('msrp').value) || 0;
var negotiatedPrice = parseFloat(document.getElementById('negotiatedPrice').value) || 0;
var downPayment = parseFloat(document.getElementById('downPayment').value) || 0;
var tradeIn = parseFloat(document.getElementById('tradeIn').value) || 0;
var term = parseInt(document.getElementById('leaseTerm').value) || 1;
var residualPercent = parseFloat(document.getElementById('residualPercent').value) || 0;
var moneyFactor = parseFloat(document.getElementById('moneyFactor').value) || 0;
var salesTax = parseFloat(document.getElementById('salesTax').value) || 0;
// 1. Calculate Net Capitalized Cost
var netCapCost = negotiatedPrice – downPayment – tradeIn;
// 2. Calculate Residual Value
var residualValue = msrp * (residualPercent / 100);
// 3. Calculate Monthly Depreciation
var totalDepreciation = netCapCost – residualValue;
var monthlyDepreciation = totalDepreciation / term;
// 4. Calculate Monthly Finance Fee (Money Factor Logic)
var monthlyFinanceFee = (netCapCost + residualValue) * moneyFactor;
// 5. Subtotal and Tax
var baseMonthlyPayment = monthlyDepreciation + monthlyFinanceFee;
var monthlyTax = baseMonthlyPayment * (salesTax / 100);
var totalMonthlyPayment = baseMonthlyPayment + monthlyTax;
// 6. Total Out of Pocket
var totalCost = (totalMonthlyPayment * term) + downPayment + tradeIn;
// Display Results
document.getElementById('monthlyResult').innerText = '$' + totalMonthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalDepreciation').innerText = '$' + totalDepreciation.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('monthlyFinance').innerText = '$' + monthlyFinanceFee.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalLeaseCost').innerText = '$' + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resultArea').style.display = 'block';
}
How to Use the Car Lease Calculator
Leasing a vehicle can be more complex than a traditional purchase because of how the math is structured. To get an accurate estimate, you need to understand three core components: Capitalized Cost, Residual Value, and the Money Factor.
Key Terms Explained
Negotiated Price (Gross Cap Cost): This is the final price of the car you agree upon with the dealer. Never lease based on the MSRP; always negotiate the sales price first.
Residual Value: This is the estimated value of the car at the end of the lease. It is set by the bank, not the dealer. A higher residual value usually results in a lower monthly payment.
Money Factor: This represents the interest rate on the lease. To convert this to a familiar APR, multiply the money factor by 2,400. For example, 0.0015 x 2400 = 3.6% APR.
Down Payment (Cap Cost Reduction): Cash paid upfront to lower the capitalized cost. Note: In leasing, a large down payment is often discouraged because if the car is totaled or stolen early in the lease, you may not get that money back.
Example Calculation
Suppose you are looking at a car with an MSRP of $40,000. You negotiate the price down to $37,000. The bank sets a 36-month residual at 60% ($24,000). With a money factor of 0.00125 and $2,000 down:
Base Payment: $305.56 + $73.75 = $379.31 (plus local taxes)
Pro Tips for a Better Lease Deal
To ensure you get the best deal possible, always ask the dealer for the "buy rate" money factor to ensure they aren't marking up the interest rate. Additionally, check for manufacturer "lease specials" where the residual value might be artificially inflated or the money factor subsidized to move specific inventory.