function calculateLease() {
var msrp = parseFloat(document.getElementById('msrp').value);
var salesPrice = parseFloat(document.getElementById('salesPrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var tradeIn = parseFloat(document.getElementById('tradeIn').value);
var term = parseInt(document.getElementById('leaseTerm').value);
var residualPercent = parseFloat(document.getElementById('residualPercent').value);
var moneyFactor = parseFloat(document.getElementById('moneyFactor').value);
var salesTax = parseFloat(document.getElementById('salesTax').value);
if (isNaN(msrp) || isNaN(salesPrice) || isNaN(downPayment) || isNaN(moneyFactor)) {
alert("Please enter valid numeric values.");
return;
}
// Calculation Logic
var capCost = salesPrice – downPayment – tradeIn;
var residualValue = msrp * (residualPercent / 100);
// Monthly Depreciation Fee
var monthlyDepreciation = (capCost – residualValue) / term;
if (monthlyDepreciation < 0) monthlyDepreciation = 0;
// Monthly Rent Charge (Interest)
var monthlyRentCharge = (capCost + residualValue) * moneyFactor;
// Base Payment
var basePayment = monthlyDepreciation + monthlyRentCharge;
// Monthly Tax
var monthlyTax = basePayment * (salesTax / 100);
// Total Monthly Payment
var totalMonthlyPayment = basePayment + monthlyTax;
var totalLeaseCost = (totalMonthlyPayment * term) + downPayment + tradeIn;
// Display Results
document.getElementById('monthlyPayment').innerText = '$' + totalMonthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resValDisplay').innerText = '$' + residualValue.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('depreciationDisplay').innerText = '$' + monthlyDepreciation.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('rentDisplay').innerText = '$' + monthlyRentCharge.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalCostDisplay').innerText = '$' + totalLeaseCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('leaseResult').style.display = 'block';
}
How to Use the Car Lease Calculator
Understanding the math behind your car lease can save you thousands of dollars at the dealership. This calculator breaks down the three primary components of a lease payment: depreciation, the rent charge (interest), and sales tax.
Key Lease Terms Explained
MSRP: The Manufacturer's Suggested Retail Price. This is used to calculate the residual value.
Negotiated Price (Capitalized Cost): This is the actual price you agree to pay for the car. You should always negotiate this just like you would for a car purchase.
Money Factor: This is the interest rate for the lease. To convert this to a standard APR, multiply it by 2,400. (e.g., 0.00125 x 2400 = 3% APR).
Residual Value: The estimated value of the car at the end of the lease. A higher residual value usually results in a lower monthly payment.
Realistic Leasing Example
Imagine you are looking at a luxury SUV with an MSRP of $50,000. You negotiate the price down to $47,000 and put $3,000 down. If the bank sets a 36-month residual at 60% ($30,000) and gives you a money factor of 0.00150:
Monthly Rent Charge: ($44,000 + $30,000) x 0.00150 = $111.00
Base Payment: $388.89 + $111.00 = $499.89
After adding a standard 7% sales tax, your final payment would be approximately $534.88 per month.
3 Tips for a Better Lease Deal
1. Negotiate the Sale Price: Most people think lease payments are set in stone. They aren't. Negotiate the "Capitalized Cost" before you ever mention leasing.
2. Avoid Large Down Payments: In a lease, if the car is totaled or stolen, that down payment is often lost. Try to put as little down as possible ("Sign and Drive").
3. Check the Money Factor: Dealers often "mark up" the money factor provided by the bank. Ask for the "buy rate" to ensure you are getting the best interest rate possible.