Estimated Loan Amount:$0.00 Total Out-of-Pocket:$0.00
*This includes your estimated sales tax and excludes registration fees.
How Much Car Can I Afford?
Determining your car buying budget is more complex than just looking at the sticker price. To truly understand your vehicle affordability, you must consider the interplay between your monthly budget, interest rates, and the total length of the loan. Our Car Loan Affordability Calculator helps you work backward from a monthly payment you're comfortable with to find the maximum purchase price of a vehicle.
The 20/4/10 Rule for Car Buying
Financial experts often recommend the "20/4/10" rule to ensure you aren't overextending your finances on a depreciating asset:
20% Down Payment: Aim to put at least 20% down to avoid being "underwater" (owing more than the car is worth) immediately.
4-Year Loan Term: Keep the loan duration to 48 months (4 years) to minimize interest costs.
10% of Income: Your total transportation costs (loan payment, insurance, gas, maintenance) should not exceed 10% of your gross monthly income.
Key Factors That Impact Affordability
Several variables determine how much car you can actually bring home:
Credit Score: A higher credit score secures lower interest rates, which directly increases the amount of car you can afford for the same monthly payment.
Loan Term: Stretching a loan to 72 or 84 months makes the monthly payment lower, but you will pay significantly more in total interest.
Trade-in Value: If you have a vehicle to trade in, it acts as a "cash" down payment, reducing the taxable amount in many states and lowering your loan balance.
Sales Tax: Don't forget that the price you see on the window isn't the final price. Sales tax can add thousands of dollars to the final bill.
Example Calculation
If you have a budget of $500 per month, a $5,000 down payment, and you qualify for a 5% interest rate over 60 months, you can afford a car priced at approximately $31,500 (assuming a 6% sales tax). Without that down payment, your purchasing power drops to roughly $26,500.
function calculateAffordability() {
var monthlyPayment = parseFloat(document.getElementById("monthlyPayment").value);
var downPayment = parseFloat(document.getElementById("downPayment").value) || 0;
var tradeIn = parseFloat(document.getElementById("tradeIn").value) || 0;
var annualRate = parseFloat(document.getElementById("interestRate").value);
var months = parseInt(document.getElementById("loanTerm").value);
var taxRate = parseFloat(document.getElementById("salesTax").value) / 100;
if (isNaN(monthlyPayment) || isNaN(annualRate) || isNaN(months) || monthlyPayment <= 0) {
alert("Please enter valid numbers for payment, rate, and term.");
return;
}
// Convert annual rate to monthly decimal
var monthlyRate = annualRate / 100 / 12;
// Formula for Present Value of an Annuity (Loan Amount)
// P = PMT * [(1 – (1 + r)^-n) / r]
var loanAmount = 0;
if (monthlyRate === 0) {
loanAmount = monthlyPayment * months;
} else {
loanAmount = monthlyPayment * ((1 – Math.pow(1 + monthlyRate, -months)) / monthlyRate);
}
// Total buying power (Before Tax)
// Vehicle Price + (Vehicle Price * Tax) = Loan + Down + Trade
// Vehicle Price * (1 + Tax) = Loan + Down + Trade
// Vehicle Price = (Loan + Down + Trade) / (1 + Tax)
var totalAffordablePrice = (loanAmount + downPayment + tradeIn) / (1 + taxRate);
// Display Results
document.getElementById("result-area").style.display = "block";
document.getElementById("totalVehiclePrice").innerText = formatCurrency(totalAffordablePrice);
document.getElementById("loanAmountResult").innerText = formatCurrency(loanAmount);
document.getElementById("outOfPocket").innerText = formatCurrency(downPayment);
// Scroll to result on mobile
document.getElementById("result-area").scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}
function formatCurrency(value) {
return "$" + value.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
}