Please enter valid numeric values for price and interest rate.
Estimated Monthly Payment$0.00
Total Amount Financed:$0.00
Total Interest Cost:$0.00
Sales Tax Amount:$0.00
Total Cost of Vehicle (All incl.):$0.00
Understanding Your Car Loan Options
Financing a vehicle is a major financial decision. Using a Car Loan Calculator helps you understand exactly how much you will pay each month and over the life of the loan. Unlike a simple mortgage calculator, car loans involve specific variables like trade-in values and vehicle sales tax which significantly impact your bottom line.
Key Factors Affecting Your Monthly Payment
When you calculate your car loan payments, several distinct factors come into play:
Vehicle Price: The negotiated sticker price of the car.
Trade-In Value: The amount the dealership offers for your old vehicle. This acts as a credit against the new car's price, reducing the amount you need to borrow.
Sales Tax: Often overlooked, vehicle sales tax can add thousands to your loan. In many states, you only pay tax on the difference between the new car price and your trade-in value.
Loan Term: Common terms range from 36 to 84 months. While a longer term (like 72 or 84 months) lowers your monthly payment, it drastically increases the total interest you pay.
APR (Annual Percentage Rate): Your interest rate is determined by your credit score and current market conditions. Even a 1% difference can save you hundreds of dollars.
How to Use This Calculator
To get the most accurate estimate, enter the full price of the vehicle before incentives. Input your down payment and the value of any trade-in vehicle. Don't forget the sales tax rate for your local area (state + county + city), as this is financed into the loan if not paid upfront.
Smart Car Buying Tips
Experts generally recommend the "20/4/10" rule for car buying: put at least 20% down, finance for no more than 4 years (48 months), and ensure your monthly payment (including insurance) doesn't exceed 10% of your gross monthly income. This strategy prevents you from becoming "upside-down" on your loan, where you owe more than the car is worth.
function calculateCarLoan() {
// 1. Get Input Values
var priceInput = document.getElementById('vehiclePrice').value;
var downInput = document.getElementById('downPayment').value;
var tradeInput = document.getElementById('tradeInValue').value;
var taxInput = document.getElementById('salesTax').value;
var rateInput = document.getElementById('interestRate').value;
var termInput = document.getElementById('loanTerm').value;
// 2. Parse and Validate
var price = parseFloat(priceInput);
var down = parseFloat(downInput) || 0;
var trade = parseFloat(tradeInput) || 0;
var taxRate = parseFloat(taxInput) || 0;
var interestRate = parseFloat(rateInput);
var months = parseInt(termInput);
var errorDiv = document.getElementById('errorMsg');
var resultsDiv = document.getElementById('results');
if (isNaN(price) || isNaN(interestRate) || price Price, taxable is 0.
// Note: Some states tax the full price. This calculator assumes tax credit for trade-in.
var taxableAmount = Math.max(0, price – trade);
var taxAmount = taxableAmount * (taxRate / 100);
// Calculate Amount Financed
// Financed = Price + Tax – Down Payment – TradeIn
// Note: If (Down + Trade) > (Price + Tax), financed is 0.
var totalCostBase = price + taxAmount;
var upfrontCredits = down + trade;
var principal = Math.max(0, totalCostBase – upfrontCredits);
var monthlyPayment = 0;
var totalInterest = 0;
var totalCost = 0;
if (principal > 0) {
if (interestRate === 0) {
monthlyPayment = principal / months;
totalInterest = 0;
} else {
var monthlyRate = (interestRate / 100) / 12;
// Formula: M = P * [ r(1+r)^n ] / [ (1+r)^n – 1 ]
var x = Math.pow(1 + monthlyRate, months);
monthlyPayment = (principal * x * monthlyRate) / (x – 1);
totalInterest = (monthlyPayment * months) – principal;
}
}
// Total cost of vehicle = Down + Trade + (Monthly * Months)
// Or simply: Price + Tax + Interest
// Wait, technically Total Cost usually means Price + Tax + Interest.
// The amount "out of pocket" + value of trade.
totalCost = totalCostBase + totalInterest;
// 4. Update UI
document.getElementById('monthlyPayment').innerText = formatMoney(monthlyPayment);
document.getElementById('amountFinanced').innerText = formatMoney(principal);
document.getElementById('totalInterest').innerText = formatMoney(totalInterest);
document.getElementById('totalTax').innerText = formatMoney(taxAmount);
document.getElementById('totalCost').innerText = formatMoney(totalCost);
resultsDiv.style.display = 'block';
}
function formatMoney(amount) {
return '$' + amount.toLocaleString('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
}