Auto Loan Refinance Calculator – Navy Federal
Estimated New Monthly Payment:
Monthly Savings:
Total Interest Savings:
function calculateRefinance() {
const currentLoanBalance = parseFloat(document.getElementById(‘currentLoanBalance’).value);
const interestRate = parseFloat(document.getElementById(‘interestRate’).value) / 100;
const loanTerm = parseInt(document.getElementById(‘loanTerm’).value) * 12; // months
const newRate = parseFloat(document.getElementById(‘newRate’).value) / 100;
const newTerm = parseInt(document.getElementById(‘newTerm’).value) * 12; // months
const currentMonthlyPayment = parseFloat(document.getElementById(‘monthlyPayment’).value);
if (isNaN(currentLoanBalance) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(newRate) || isNaN(newTerm) || isNaN(currentMonthlyPayment)) {
alert(‘Please fill in all fields with valid values.’);
return;
}
// Current loan calculations
const currentMonthlyRate = interestRate / 12;
const currentMonthlyPaymentCalc = currentLoanBalance * currentMonthlyRate / (1 – Math.pow(1 + currentMonthlyRate, -loanTerm));
// New loan calculations
const newMonthlyRate = newRate / 12;
const newMonthlyPayment = currentLoanBalance * newMonthlyRate / (1 – Math.pow(1 + newMonthlyRate, -newTerm));
// Calculate savings
const monthlySavings = currentMonthlyPaymentCalc – newMonthlyPayment;
const interestSavings = (currentMonthlyPaymentCalc * loanTerm – currentLoanBalance) – (newMonthlyPayment * newTerm – currentLoanBalance);
// Display results
document.getElementById(‘newPayment’).innerText = newMonthlyPayment.toFixed(2);
document.getElementById(‘monthlySavings’).innerText = monthlySavings.toFixed(2);
document.getElementById(‘interestSavings’).innerText = interestSavings.toFixed(2);
}
