function calculateLeasePayment() {
var msrp = parseFloat(document.getElementById("msrp").value);
var salesPrice = parseFloat(document.getElementById("salesPrice").value);
var downPayment = parseFloat(document.getElementById("downPayment").value) || 0;
var tradeIn = parseFloat(document.getElementById("tradeIn").value) || 0;
var term = parseInt(document.getElementById("leaseTerm").value);
var residualPercent = parseFloat(document.getElementById("residualPercent").value);
var moneyFactor = parseFloat(document.getElementById("moneyFactor").value);
var taxRate = parseFloat(document.getElementById("taxRate").value) / 100;
if (isNaN(msrp) || isNaN(salesPrice) || isNaN(term) || isNaN(residualPercent) || isNaN(moneyFactor)) {
alert("Please enter valid numbers in all required fields.");
return;
}
// 1. Calculate Gross Cap Cost
var capCost = salesPrice – downPayment – tradeIn;
// 2. Calculate Residual Value
var residualValue = msrp * (residualPercent / 100);
// 3. Monthly Depreciation
var monthlyDepreciation = (capCost – residualValue) / term;
if (monthlyDepreciation < 0) monthlyDepreciation = 0;
// 4. Monthly Finance Charge (Rent Charge)
var monthlyFinance = (capCost + residualValue) * moneyFactor;
// 5. Subtotal and Tax
var basePayment = monthlyDepreciation + monthlyFinance;
var monthlyTax = basePayment * taxRate;
// 6. Total Payment
var totalPayment = basePayment + monthlyTax;
// Update DOM
document.getElementById("resCapCost").innerText = "$" + capCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resResidual").innerText = "$" + residualValue.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resDepreciation").innerText = "$" + monthlyDepreciation.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resFinance").innerText = "$" + monthlyFinance.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resTax").innerText = "$" + monthlyTax.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("resTotal").innerText = "$" + totalPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById("leaseResult").style.display = "block";
}
Understanding How Your Car Lease Payment is Calculated
Leasing a car can be a complex financial arrangement. Unlike a traditional auto loan where you pay down the entire value of the vehicle, a lease essentially pays for the vehicle's depreciation during the time you drive it, plus interest and taxes.
Key Components of a Car Lease
- Gross Capitalized Cost: This is the negotiated price of the vehicle. To get a lower payment, you must negotiate this price just as you would if you were buying the car.
- Residual Value: This is the estimated value of the car at the end of the lease term. It is set by the leasing company. A higher residual value usually results in a lower monthly payment.
- Money Factor: This represents the interest rate on a lease. To convert the money factor to a standard APR, multiply it by 2400. For example, a money factor of 0.00125 equals a 3% APR.
- Lease Term: The duration of the lease, typically expressed in months (e.g., 24, 36, or 48 months).
The Math Behind the Lease
The calculation consists of three main parts: Depreciation, Finance Charge, and Tax.
1. Depreciation Fee: (Net Cap Cost – Residual Value) / Term. This covers the loss in the car's value while you use it.
2. Finance Fee (Rent Charge): (Net Cap Cost + Residual Value) × Money Factor. This is the fee for the "borrowed" value of the vehicle.
3. Sales Tax: In most states, sales tax is applied to the monthly payment rather than the full value of the vehicle.
Example Calculation
Imagine you are leasing a car with an MSRP of $40,000. You negotiate the price down to $38,000. You put $2,000 down, making your Cap Cost $36,000. If the 36-month residual is 60% ($24,000) and the money factor is 0.0015:
- Monthly Depreciation: ($36,000 – $24,000) / 36 = $333.33
- Monthly Finance Charge: ($36,000 + $24,000) × 0.0015 = $90.00
- Base Payment: $333.33 + $90.00 = $423.33
- With 7% Tax: $423.33 + $29.63 = $452.96 Total
How to Get the Best Lease Deal
To minimize your monthly payment, focus on three things: negotiating a lower sales price, choosing a vehicle with a high residual value, and ensuring you have a competitive money factor based on your credit score. Avoid putting too much money down on a lease (Cap Cost Reduction), as you may lose that money if the vehicle is totaled early in the term.