Calculate your estimated monthly payment for a new or used GM vehicle. Enter the vehicle price, down payment, interest rate, and loan term to see your potential monthly cost.
Understanding Your GM Vehicle Payment
Financing a General Motors (GM) vehicle, whether it's a Chevrolet, GMC, Buick, or Cadillac, involves understanding how your monthly payment is calculated. This calculator helps estimate that payment, but it's important to know the factors that influence it.
The Formula Behind the Payment
The standard formula for calculating a fixed-rate loan payment is as follows:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Your total monthly loan payment.
P = The principal loan amount (Vehicle Price – Down Payment).
i = Your *monthly* interest rate. To get this, divide your annual interest rate by 12 (e.g., 5% annual / 12 months = 0.05 / 12 = 0.004167).
n = The total number of payments over the loan's lifetime (Loan Term in Months).
How the Calculator Works
Vehicle Price: The sticker price or agreed-upon price of the GM vehicle you intend to purchase.
Down Payment: The amount of money you pay upfront. A larger down payment reduces the principal loan amount (P), leading to lower monthly payments and potentially less interest paid over the life of the loan.
Principal Loan Amount (P): Calculated as Vehicle Price minus Down Payment. This is the actual amount you are borrowing.
Annual Interest Rate: The yearly percentage charged by the lender. This is converted to a monthly rate (i) for the calculation. A lower interest rate significantly reduces your monthly payment and the total interest paid.
Loan Term (Months) (n): The duration of the loan in months. A longer loan term will result in lower monthly payments but typically means paying more interest overall. Shorter terms mean higher monthly payments but less total interest.
The calculator takes these inputs, converts the annual interest rate to a monthly rate, calculates the principal loan amount, and then applies the loan payment formula to provide an estimated monthly payment (M).
Important Considerations:
Estimates Only: This calculator provides an estimate. Actual loan terms, rates, fees, and dealer incentives can vary.
Taxes, Fees, and Add-ons: The calculation does not include taxes, registration fees, dealer-installed accessories, or extended warranties, which would increase your total out-of-pocket cost.
Lease vs. Loan: This calculator is for financing (loan) a vehicle, not for calculating lease payments, which follow a different structure.
Creditworthiness: Interest rates are highly dependent on your credit score and financial history. Special financing offers from GM Financial may have specific eligibility requirements.
Use this tool to get a better understanding of potential monthly costs and to budget effectively for your next GM vehicle purchase.
function calculatePayment() {
var vehiclePrice = parseFloat(document.getElementById("vehiclePrice").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseInt(document.getElementById("loanTerm").value);
var resultElement = document.getElementById("result");
// Clear previous results
resultElement.innerHTML = "";
// Input validation
if (isNaN(vehiclePrice) || vehiclePrice <= 0) {
resultElement.innerHTML = "Please enter a valid Vehicle Price.";
return;
}
if (isNaN(downPayment) || downPayment < 0) {
resultElement.innerHTML = "Please enter a valid Down Payment.";
return;
}
if (isNaN(interestRate) || interestRate < 0) {
resultElement.innerHTML = "Please enter a valid Annual Interest Rate.";
return;
}
if (isNaN(loanTerm) || loanTerm vehiclePrice) {
resultElement.innerHTML = "Down Payment cannot be greater than Vehicle Price.";
return;
}
var principal = vehiclePrice – downPayment;
var monthlyInterestRate = (interestRate / 100) / 12;
var monthlyPayment;
if (monthlyInterestRate > 0) {
// M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
var numerator = monthlyInterestRate * Math.pow(1 + monthlyInterestRate, loanTerm);
var denominator = Math.pow(1 + monthlyInterestRate, loanTerm) – 1;
monthlyPayment = principal * (numerator / denominator);
} else {
// If interest rate is 0, payment is simply principal / term
monthlyPayment = principal / loanTerm;
}
// Format the result to two decimal places and add currency symbol
var formattedPayment = "$" + monthlyPayment.toFixed(2);
resultElement.innerHTML = formattedPayment + "Estimated Monthly Payment";
}
function updateSlider(inputId, sliderId) {
var inputElement = document.getElementById(inputId);
var sliderElement = document.getElementById(sliderId);
sliderElement.value = inputElement.value;
// If the input is not the rate, call calculatePayment immediately
if (inputId !== 'interestRate') {
calculatePayment();
}
}
function updateInput(sliderId, inputId) {
var sliderElement = document.getElementById(sliderId);
var inputElement = document.getElementById(inputId);
inputElement.value = sliderElement.value;
calculatePayment();
}
// Initial calculation on page load
window.onload = function() {
calculatePayment();
};