Please enter valid positive numbers for all fields.
Principal & Interest:$0.00
Monthly Property Tax:$0.00
Monthly Home Insurance:$0.00
HOA / PMI:$0.00
Total Monthly Payment (PITI):$0.00
Total Interest Paid (Life of Loan):$0.00
Understanding Your Mortgage PITI Payment
When shopping for a home, looking at the listing price is just the tip of the iceberg. To truly understand affordability, you must calculate the PITI payment. PITI stands for Principal, Interest, Taxes, and Insurance. This calculator provides a comprehensive breakdown of your monthly financial obligation, ensuring there are no surprises at the closing table.
The 4 Components of a Mortgage Payment
Principal: The portion of your payment that goes directly toward reducing the loan balance. In the early years of a standard amortization schedule, this amount is small but grows over time.
Interest: The cost of borrowing money from your lender. Determined by your Annual Percentage Rate (APR). Higher rates significantly increase your monthly costs and the total cost of the loan.
Taxes: Property taxes are assessed by your local government to fund schools, roads, and services. Lenders typically collect this monthly and hold it in an escrow account to pay the annual bill.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is usually divided into monthly payments and held in escrow.
Why the "Monthly HOA / PMI" Field Matters
Many homebuyers forget to factor in homeowner association (HOA) fees or Private Mortgage Insurance (PMI). If you put down less than 20% of the home's value, lenders usually require PMI. Additionally, condos and planned communities often have mandatory HOA dues. Adding these to your calculation gives you a realistic "out-the-door" monthly cost.
How Interest Rates Impact Affordability
Even a small fluctuation in interest rates can drastically change your purchasing power. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate is roughly $200 per month. Use the inputs above to scenario-test different rates to see how they affect your budget.
function calculateMortgage() {
// 1. Get Elements
var homePriceInput = document.getElementById("mg_homePrice");
var downPaymentInput = document.getElementById("mg_downPayment");
var interestRateInput = document.getElementById("mg_interestRate");
var loanTermInput = document.getElementById("mg_loanTerm");
var propertyTaxInput = document.getElementById("mg_propertyTax");
var homeInsuranceInput = document.getElementById("mg_homeInsurance");
var hoaInput = document.getElementById("mg_hoa");
var errorDiv = document.getElementById("mg_error");
var resultsDiv = document.getElementById("mg_results");
// 2. Parse Values
var homePrice = parseFloat(homePriceInput.value);
var downPayment = parseFloat(downPaymentInput.value);
var interestRate = parseFloat(interestRateInput.value);
var loanTermYears = parseFloat(loanTermInput.value);
var annualTax = parseFloat(propertyTaxInput.value);
var annualInsurance = parseFloat(homeInsuranceInput.value);
var monthlyHoa = parseFloat(hoaInput.value);
// 3. Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) ||
isNaN(loanTermYears) || isNaN(annualTax) || isNaN(annualInsurance) || isNaN(monthlyHoa)) {
errorDiv.style.display = "block";
resultsDiv.style.display = "none";
return;
}
if (homePrice < 0 || downPayment < 0 || interestRate < 0 || loanTermYears <= 0) {
errorDiv.style.display = "block";
errorDiv.innerHTML = "Values cannot be negative. Term must be greater than 0.";
resultsDiv.style.display = "none";
return;
}
// Hide error if valid
errorDiv.style.display = "none";
// 4. Calculations
var loanAmount = homePrice – downPayment;
// Handle case where down payment is greater than home price
if (loanAmount 0) {
if (interestRate === 0) {
monthlyPrincipalInterest = loanAmount / numberOfPayments;
} else {
monthlyPrincipalInterest = loanAmount *
(monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) /
(Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
}
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + monthlyHoa;
var totalCostOfLoan = (monthlyPrincipalInterest * numberOfPayments);
var totalInterest = totalCostOfLoan – loanAmount;
// 5. Update UI
// Helper function for currency format
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
document.getElementById("res_pi").innerText = formatter.format(monthlyPrincipalInterest);
document.getElementById("res_tax").innerText = formatter.format(monthlyTax);
document.getElementById("res_ins").innerText = formatter.format(monthlyInsurance);
document.getElementById("res_hoa").innerText = formatter.format(monthlyHoa);
document.getElementById("res_total").innerText = formatter.format(totalMonthlyPayment);
document.getElementById("res_totalInterest").innerText = formatter.format(totalInterest);
// Show results
resultsDiv.style.display = "block";
}