Enter your loan details to see the payoff savings.
Understanding Your Auto Loan Payoff
An auto loan can be a significant financial commitment. While making your regular monthly payments is essential, accelerating your loan payoff can save you a substantial amount of money in interest over the life of the loan and help you become debt-free sooner. This Auto Loan Payoff Calculator helps you estimate the impact of making extra payments on your loan's duration and the total interest you'll save.
How the Calculator Works
The calculator uses your current loan details and any additional monthly payments you plan to make to determine:
The new payoff timeline (how much sooner you'll be debt-free).
The total interest saved by making extra payments.
The Math Behind Auto Loans
Auto loans typically use an amortizing loan structure. This means that each monthly payment is divided into two parts: principal and interest. Initially, a larger portion of your payment goes towards interest, and as the loan progresses, more goes towards the principal.
The formula for a standard monthly loan payment (M) is:
n = Total Number of Payments (Loan Term in Months)
When you make an extra payment, that entire amount (beyond covering your regular interest and principal due for that month) goes directly towards reducing the principal balance. A lower principal balance means less interest accrues in subsequent periods, accelerating the payoff and reducing total interest paid.
Why Pay Off Your Auto Loan Early?
Save Money: The most significant benefit is reducing the total interest paid over the loan's life. Even small extra payments can add up to considerable savings.
Become Debt-Free Faster: Achieving financial freedom sooner can reduce stress and open up opportunities for other financial goals, like saving for a down payment on a home or investing.
Improve Debt-to-Income Ratio: Lowering your overall debt can positively impact your credit score and make it easier to qualify for future loans or credit.
Peace of Mind: Owning your car outright provides a great sense of security and eliminates a recurring monthly expense.
How to Use the Calculator
Original Loan Amount: Enter the total amount you borrowed for the car.
Annual Interest Rate: Input the interest rate as a percentage (e.g., 5.5 for 5.5%).
Original Loan Term: Specify the total number of months you agreed to pay the loan back over (e.g., 60 for a 5-year loan).
Current Loan Balance: Enter how much you still owe on the loan.
Extra Monthly Payment: This is the key! Enter any additional amount you plan to pay each month above your scheduled payment. If you can't commit to a specific amount, start with a small figure to see its potential impact.
Click "Calculate Payoff" to see how much time and money you could save.
Disclaimer: This calculator provides an estimate. Actual savings may vary due to specific lender policies, payment timing, and potential fees. Always consult your loan agreement and lender for precise details.
function calculatePayoff() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTermMonths = parseInt(document.getElementById("loanTermMonths").value);
var currentBalance = parseFloat(document.getElementById("currentBalance").value);
var extraPayment = parseFloat(document.getElementById("extraPayment").value);
var resultDiv = document.getElementById("result");
// Validate inputs
if (isNaN(loanAmount) || isNaN(interestRate) || isNaN(loanTermMonths) || isNaN(currentBalance) || isNaN(extraPayment) ||
loanAmount <= 0 || interestRate < 0 || loanTermMonths <= 0 || currentBalance < 0 || extraPayment loanAmount) {
resultDiv.innerHTML = "Current balance cannot be greater than the original loan amount.";
resultDiv.style.backgroundColor = "#dc3545"; // Error color
return;
}
var monthlyInterestRate = (interestRate / 100) / 12;
// Calculate original monthly payment (needed to determine total interest paid)
var originalMonthlyPayment = 0;
if (monthlyInterestRate > 0) {
originalMonthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, loanTermMonths)) / (Math.pow(1 + monthlyInterestRate, loanTermMonths) – 1);
} else {
originalMonthlyPayment = loanAmount / loanTermMonths; // Simple division if interest is 0
}
// — Simulation with Extra Payments —
var simulatedBalance = currentBalance;
var monthsPaid = 0;
var totalInterestPaidWithExtra = 0;
var tempMonthlyInterest = 0;
var tempPrincipalPaid = 0;
// If current balance is already paid off or less than scheduled payment, adjust logic
if (simulatedBalance 0) {
// Calculate interest for the current month based on the remaining balance
tempMonthlyInterest = simulatedBalance * monthlyInterestRate;
// Check if paying only interest exceeds the remaining balance
if (tempMonthlyInterest >= simulatedBalance && monthlyInterestRate > 0) {
// This happens when the remaining balance is very small and interest accrues more than the balance itself.
// This usually means the loan is effectively paid off or very close.
// If we hit this and simulatedBalance > 0, it means the last payment will be the balance + last month's interest.
// Add remaining balance and interest and break.
totalInterestPaidWithExtra += simulatedBalance; // Effectively, all remaining balance is interest in this edge case
simulatedBalance = 0;
monthsPaid++; // Count this final "payment"
break;
}
// Determine principal payment for this month
// If the total payment (original + extra) is less than the balance + monthly interest,
// it means they can't even cover the interest + principal with the extra payment strategy.
// This is an edge case, we assume they can at least cover interest.
var principalPaymentThisMonth = totalMonthlyPayment – tempMonthlyInterest;
// Ensure principal payment doesn't exceed the remaining balance
if (principalPaymentThisMonth > simulatedBalance) {
principalPaymentThisMonth = simulatedBalance;
totalMonthlyPayment = principalPaymentThisMonth + tempMonthlyInterest; // Adjust total payment to only cover remaining balance + interest
}
if (principalPaymentThisMonth loanTermMonths * 5 && simulatedBalance > 0) { // Arbitrary limit to prevent runaway loops
resultDiv.innerHTML = "Calculation could not complete. Please check your inputs or loan terms.";
resultDiv.style.backgroundColor = "#dc3545"; // Error color
return;
}
}
// — Calculate total interest paid without extra payments (based on current balance and original payment terms) —
// We need to determine how many payments are left on the *original* loan from the current balance.
// This is complex because the original payment was calculated for the *original* loan amount and term.
// A simpler approach for comparison: calculate the total interest from the *current balance* if paid off at the *original payment rate* without extra payments.
// However, this isn't a fair comparison if the original loan term is much longer.
// A more accurate comparison: how much total interest is paid from the CURRENT BALANCE up to the ORIGINAL LOAN TERM END.
// Let's use a slightly different logic: Calculate total interest IF they continue paying the *original monthly payment* starting from the *current balance* until the *original loan term ends*.
var originalMonthsRemaining = loanTermMonths; // Approximation, ideally we'd calculate remaining months based on current balance and original payment
var tempBalanceForOriginalCalc = currentBalance;
var totalInterestPaidOriginal = 0;
var originalPaymentsMade = 0;
// Re-calculate total interest IF they just paid the original monthly payment from current balance until original term ends (or balance is paid off)
// This requires knowing how many months *remain* on the original loan to reach the original term, or until balance is paid.
// A simpler, more common comparison for "early payoff savings" is to compare the total interest paid with extra payments
// versus the total interest paid if they *only* paid the minimum required principal and interest from the *current balance* onwards.
// Let's simulate paying from current balance with *only* the original monthly payment, until balance is zero.
var balanceForComparison = currentBalance;
var monthsForComparison = 0;
var interestPaidForComparison = 0;
var paymentForComparison = originalMonthlyPayment; // Use the calculated original monthly payment
// Edge case: If originalMonthlyPayment is less than the interest on current balance, this simulation will fail.
// This implies the original loan was structured poorly or the user entered incorrect info.
// In a real amortization, the payment would adjust to cover interest + principal.
// If they ONLY pay originalMonthlyPayment, and it's less than interest, they'd never pay it off.
// For this calculation, let's assume they continue making *at least* the interest, and the remainder is principal.
// The most direct comparison is: how much interest do they pay if they *stick to the original payment* vs *adding extra*.
// Let's calculate total interest paid if they *only* paid the original monthly payment from the current balance until it's paid off.
// This is a common way to show savings from extra payments.
var balanceForOriginalPayoff = currentBalance;
var monthsToPayOffOriginal = 0;
var totalInterestIfOriginalPayment = 0;
var calculatedMonthlyPayment = originalMonthlyPayment; // The payment calculated for original loan amount/term
// We need to find out how many months it *would* take to pay off the *current balance* using the *original monthly payment*.
// If currentBalance 0) {
var interestThisMonthOriginal = balanceForOriginalPayoff * monthlyInterestRate;
var principalThisMonthOriginal = calculatedMonthlyPayment – interestThisMonthOriginal;
// Handle case where calculatedMonthlyPayment is not enough to cover interest
if (calculatedMonthlyPayment 0) {
// This scenario implies the original loan terms are insufficient for the current balance, or invalid inputs.
// In a real loan, the payment would adjust. Here, we assume they pay just enough to cover interest and remaining balance.
// If they *only* pay `calculatedMonthlyPayment`, and it's less than interest, they'd never pay it off.
// For a fair comparison for "savings", we must ensure the base case also pays off the loan.
// A better comparison: how much interest from *current balance* until *original loan end date*.
// But we don't know the original loan end date from current balance.
// Let's re-frame: "How much interest is saved compared to paying off the *current balance* using the *original monthly payment* amount until the balance is zero?"
// This is a standard comparison.
// If calculatedMonthlyPayment is less than interest, the loan will never be paid off by making *only* that payment.
// We need to ensure the base case payment covers at least interest and some principal.
// If `calculatedMonthlyPayment` is insufficient, this implies the `currentBalance` and `originalMonthlyPayment` are inconsistent.
// Let's ensure `calculatedMonthlyPayment` is at least enough to cover interest + remaining balance.
if (interestThisMonthOriginal >= balanceForOriginalPayoff) { // The entire balance is less than interest
totalInterestIfOriginalPayment += balanceForOriginalPayoff; // Add remaining balance as "interest" effectively
balanceForOriginalPayoff = 0;
} else {
// If calculatedMonthlyPayment balanceForOriginalPayoff) {
principalThisMonthOriginal = balanceForOriginalPayoff;
calculatedMonthlyPayment = interestThisMonthOriginal + principalThisMonthOriginal; // Adjust total payment
}
balanceForOriginalPayoff -= principalThisMonthOriginal;
totalInterestIfOriginalPayment += interestThisMonthOriginal;
}
monthsToPayOffOriginal++;
if (monthsToPayOffOriginal > loanTermMonths * 5 && balanceForOriginalPayoff > 0) { // Safety break
totalInterestIfOriginalPayment = Infinity; // Indicate failure to calculate original interest
break;
}
}
var interestSaved = totalInterestIfOriginalPayment – totalInterestPaidWithExtra;
var originalMonthsToPayOff = monthsToPayOffOriginal; // Months to pay off current balance with original payment
var newMonthsToPayOff = monthsPaid;
var timeSavedMonths = originalMonthsToPayOff – newMonthsToPayOff;
var timeSavedYears = Math.floor(timeSavedMonths / 12);
var remainingTimeSavedMonths = timeSavedMonths % 12;
var outputString = "";
if (interestSaved > 0) {
outputString = "You could save an estimated $" + interestSaved.toFixed(2) + " in interest. ";
if (timeSavedYears > 0 || remainingTimeSavedMonths > 0) {
outputString += "You could pay off your loan approximately ";
if (timeSavedYears > 0) {
outputString += "" + timeSavedYears + " year(s) ";
}
if (remainingTimeSavedMonths > 0) {
outputString += "" + remainingTimeSavedMonths + " month(s) ";
}
outputString += "sooner!";
} else {
// This case occurs if timeSavedMonths is 0 or negative but interest is saved.
// Usually means the payoff was already very close.
outputString += "You could pay off your loan faster!";
}
resultDiv.style.backgroundColor = "var(–success-green)";
} else if (interestSaved === 0) {
outputString = "Your extra payment will have a minimal impact on interest saved or payoff time. ";
resultDiv.style.backgroundColor = "#ffc107"; // Warning color
} else { // interestSaved 0 && originalMonthsToPayOff > 0 && totalInterestIfOriginalPayment !== Infinity) {
resultDiv.innerHTML = outputString;
} else if (totalInterestIfOriginalPayment === Infinity) {
resultDiv.innerHTML = "Could not reliably calculate savings. Please check input values.";
resultDiv.style.backgroundColor = "#dc3545"; // Error color
} else {
resultDiv.innerHTML = "Enter your loan details to see the payoff savings.";
resultDiv.style.backgroundColor = "var(–light-background)"; // Default
}
}