.calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-container {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.95rem;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
box-sizing: border-box; /* Fix padding issue */
}
.btn-calc {
background-color: #0073aa;
color: white;
border: none;
padding: 12px 24px;
font-size: 1.1rem;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
}
.btn-calc:hover {
background-color: #005177;
}
.results-area {
margin-top: 30px;
background: #fff;
padding: 20px;
border-radius: 6px;
border-left: 5px solid #0073aa;
display: none; /* Hidden by default */
}
.results-area h3 {
margin-top: 0;
color: #0073aa;
}
.result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
}
.result-val {
font-weight: bold;
font-size: 1.1rem;
}
.highlight-val {
color: #d63638;
font-size: 1.4rem;
}
.content-section {
background: #fff;
padding: 20px 0;
}
.content-section h2 {
color: #23282d;
border-bottom: 2px solid #0073aa;
padding-bottom: 10px;
margin-top: 30px;
}
.faq-box {
background: #f0f0f1;
padding: 20px;
border-radius: 5px;
margin-top: 20px;
}
.faq-item {
margin-bottom: 15px;
}
.faq-question {
font-weight: bold;
margin-bottom: 5px;
}
function calculateAutoLoan() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('vehiclePrice').value);
var down = parseFloat(document.getElementById('downPayment').value);
var trade = parseFloat(document.getElementById('tradeInValue').value);
var taxRate = parseFloat(document.getElementById('salesTax').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var term = parseFloat(document.getElementById('loanTerm').value);
// 2. Validate Inputs
if (isNaN(price)) price = 0;
if (isNaN(down)) down = 0;
if (isNaN(trade)) trade = 0;
if (isNaN(taxRate)) taxRate = 0;
if (isNaN(interestRate)) interestRate = 0;
if (isNaN(term) || term Price, taxable is 0.
var taxableAmount = price – trade;
if (taxableAmount < 0) taxableAmount = 0;
var taxAmount = taxableAmount * (taxRate / 100);
// Calculate Loan Amount (Principal)
// Principal = Price + Tax – Down – TradeIn
// OR simpler: Principal = (Price – TradeIn + Tax) – Down
var principal = (price – trade + taxAmount) – down;
if (principal <= 0) {
// If the user has paid off the car via down payment/trade-in
document.getElementById('monthlyPaymentDisplay').innerHTML = "$0.00";
document.getElementById('financedAmountDisplay').innerHTML = "$0.00";
document.getElementById('totalInterestDisplay').innerHTML = "$0.00";
document.getElementById('totalCostDisplay').innerHTML = "$" + (price + taxAmount).toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('payoffDateDisplay').innerHTML = "N/A";
document.getElementById('resultOutput').style.display = "block";
return;
}
// Calculate Monthly Payment
var monthlyPayment = 0;
var totalInterest = 0;
var monthlyRate = (interestRate / 100) / 12;
if (interestRate === 0) {
monthlyPayment = principal / term;
totalInterest = 0;
} else {
// Standard Amortization Formula: M = P * [r(1+r)^n] / [(1+r)^n – 1]
var mathPower = Math.pow(1 + monthlyRate, term);
monthlyPayment = principal * ((monthlyRate * mathPower) / (mathPower – 1));
totalInterest = (monthlyPayment * term) – principal;
}
var totalCost = price + taxAmount + totalInterest;
// Calculate Payoff Date
var today = new Date();
var payoffDate = new Date(today.setMonth(today.getMonth() + term));
var dateOptions = { month: 'long', year: 'numeric' };
var payoffString = payoffDate.toLocaleDateString('en-US', dateOptions);
// 4. Update Output HTML
document.getElementById('monthlyPaymentDisplay').innerHTML = "$" + monthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('financedAmountDisplay').innerHTML = "$" + principal.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalInterestDisplay').innerHTML = "$" + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('totalCostDisplay').innerHTML = "$" + totalCost.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('payoffDateDisplay').innerHTML = payoffString;
// Show results
document.getElementById('resultOutput').style.display = "block";
}
Auto Loan Amortization Calculator
Loan Summary
Estimated Monthly Payment:
$0.00
Total Loan Amount (financed):
$0.00
Total Interest Paid:
$0.00
Total Cost of Car (Price + Tax + Interest):
$0.00
Payoff Date:
–
Understanding Your Auto Loan Calculation
Purchasing a vehicle is a significant financial commitment. This Auto Loan Amortization Calculator helps you determine exactly how much your monthly payments will be, factoring in variables that dealerships often gloss over, such as sales tax and the impact of your trade-in value.
While many buyers focus solely on the monthly payment, it is critical to understand the Total Cost of the Car. Extending your loan term from 60 to 84 months might lower your monthly bill, but it significantly increases the total interest paid over the life of the loan.
Key Factors Affecting Your Payment
- Vehicle Price & Tax: Sales tax is typically applied to the vehicle price. In many states, your trade-in value reduces the taxable amount, saving you money upfront. Our calculator estimates tax based on the difference between the vehicle price and trade-in value.
- Down Payment: The more you put down upfront, the less you borrow. A larger down payment reduces your monthly obligation and minimizes the risk of becoming "upside-down" (owing more than the car is worth) later.
- Interest Rate (APR): This is the cost of borrowing money. Rates are determined by your credit score, the vehicle's age, and current market conditions. Even a 1% difference can save or cost you hundreds of dollars.
- Loan Term: Common terms are 36, 48, 60, 72, and 84 months. Shorter terms have higher monthly payments but lower total interest costs.
How to Use This Calculator
Enter the negotiated price of the car, your planned down payment, the value of any vehicle you are trading in, the sales tax rate for your zip code, your expected interest rate, and the number of months you wish to finance the vehicle. The calculator will instantly break down your monthly payment and total financial obligation.
Does the loan term affect my interest rate?
Yes, generally. Lenders often charge higher interest rates for longer loan terms (e.g., 72 or 84 months) because there is a higher risk of default and vehicle depreciation over a longer period.
How is sales tax calculated on a car purchase?
In most states, sales tax is calculated on the difference between the new car's price and your trade-in value. This calculator assumes this standard method. For example, if you buy a $30,000 car and trade in a $10,000 car, you only pay tax on the remaining $20,000.
What is a good APR for a car loan?
APR varies by credit score. As of 2023-2024, excellent credit scores (720+) may see rates around 5-7% for new cars, while average scores may see 7-10%. Used car rates are typically higher than new car rates.