Estimate your monthly mortgage payments accurately by including principal, interest, taxes, insurance, and HOA fees. Use our comprehensive tool below to plan your home buying budget.
Total Monthly Payment:$0.00
Principal & Interest:$0.00
Property Tax (Monthly):$0.00
Home Insurance (Monthly):$0.00
HOA Fees:$0.00
Total Loan Amount:$0.00
Total Interest Paid (Life of Loan):$0.00
Understanding Your Mortgage Calculation
Purchasing a home is likely the largest financial commitment you will make in your lifetime. Understanding the breakdown of your monthly mortgage payment is crucial for maintaining financial health. This calculator goes beyond simple principal and interest to include the "PITI" components: Principal, Interest, Taxes, and Insurance.
The 4 Pillars of a Mortgage Payment (PITI)
Principal: The portion of your payment that goes toward paying down the actual money borrowed. In the early years of a loan, this amount is small but grows over time.
Interest: The fee charged by the lender for the privilege of borrowing money. On a 30-year fixed loan, the majority of your early payments go toward interest.
Taxes: Property taxes assessed by your local government. Lenders typically collect this monthly and hold it in an escrow account to pay the bill annually on your behalf.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is usually divided into monthly payments and held in escrow.
How Interest Rates Affect Affordability
Even a small difference in interest rates can have a massive impact on your monthly payment and the total cost of the loan. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate is roughly $200 per month, which adds up to over $70,000 in extra costs over a 30-year term.
Private Mortgage Insurance (PMI)
If your down payment is less than 20% of the home's purchase price, lenders generally require Private Mortgage Insurance (PMI). This protects the lender if you default. While our calculator includes HOA fees and standard insurance, remember to factor in PMI costs (typically 0.5% to 1% of the loan amount annually) if you are putting down less than 20%.
Tips for Lowering Your Payment
If the estimated payment is higher than your budget allows, consider these strategies:
Increase your Down Payment: This reduces the principal loan amount and may eliminate the need for PMI.
Shop for Lower Insurance Rates: Insurance premiums vary significantly between providers.
Buy "Points": You can pay an upfront fee to lower your interest rate for the life of the loan.
Extended Loan Terms: While a 15-year loan saves interest, a 30-year loan offers lower monthly payments.
function calculateMortgage() {
// 1. Get Input Values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var loanTermYears = parseFloat(document.getElementById('loanTerm').value);
var interestRateAnnual = parseFloat(document.getElementById('interestRate').value);
var propertyTaxAnnual = parseFloat(document.getElementById('propertyTax').value);
var insuranceAnnual = parseFloat(document.getElementById('insurance').value);
var hoaMonthly = parseFloat(document.getElementById('hoaFees').value);
// 2. Validate Inputs
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) || isNaN(interestRateAnnual) || isNaN(propertyTaxAnnual) || isNaN(insuranceAnnual) || isNaN(hoaMonthly)) {
alert("Please ensure all fields contain valid numbers.");
return;
}
if (loanTermYears <= 0) {
alert("Loan term must be greater than 0.");
return;
}
// 3. Core Calculations
var principal = homePrice – downPayment;
// Prevent negative loan amounts
if (principal < 0) {
principal = 0;
}
var calculatedMonthlyPI = 0;
// Handle 0% interest edge case
if (interestRateAnnual === 0) {
calculatedMonthlyPI = principal / (loanTermYears * 12);
} else {
var monthlyRate = (interestRateAnnual / 100) / 12;
var totalPayments = loanTermYears * 12;
// Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var numerator = monthlyRate * Math.pow((1 + monthlyRate), totalPayments);
var denominator = Math.pow((1 + monthlyRate), totalPayments) – 1;
calculatedMonthlyPI = principal * (numerator / denominator);
}
var monthlyTax = propertyTaxAnnual / 12;
var monthlyInsurance = insuranceAnnual / 12;
var totalMonthlyPayment = calculatedMonthlyPI + monthlyTax + monthlyInsurance + hoaMonthly;
var totalPaymentsCount = loanTermYears * 12;
var totalInterestPaid = (calculatedMonthlyPI * totalPaymentsCount) – principal;
// 4. Update UI
// Helper function for currency formatting
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
document.getElementById('resTotalMonthly').innerHTML = formatCurrency(totalMonthlyPayment);
document.getElementById('resPrincipalInterest').innerHTML = formatCurrency(calculatedMonthlyPI);
document.getElementById('resTax').innerHTML = formatCurrency(monthlyTax);
document.getElementById('resInsurance').innerHTML = formatCurrency(monthlyInsurance);
document.getElementById('resHoa').innerHTML = formatCurrency(hoaMonthly);
document.getElementById('resLoanAmount').innerHTML = formatCurrency(principal);
// If interest rate is 0, total interest is 0 (avoid negative float errors)
if (interestRateAnnual === 0) totalInterestPaid = 0;
document.getElementById('resTotalInterest').innerHTML = formatCurrency(totalInterestPaid);
// Show results container
document.getElementById('calc-results').style.display = 'block';
}