Estimate your monthly mortgage payments accurately by including Principal, Interest, Taxes, and Insurance (PITI). Use this tool to plan your budget before purchasing a home.
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Total Monthly Payment
$0.00
Loan Amount: $0
Principal & Interest$0.00
Property Tax$0.00
Home Insurance$0.00
HOA Fees$0.00
Total Interest Paid (Over Life of Loan)$0.00
Understanding Your Mortgage Payment
When buying a home, the sticker price is just the beginning. Most homebuyers finance their purchase with a mortgage, which allows them to pay off the house over time—usually 15 or 30 years. However, your monthly check written to the lender covers more than just paying back the money you borrowed.
What is Included in PITI?
Lenders often refer to your monthly payment as PITI, which stands for the four main components of a mortgage payment:
Principal: The portion of your payment that reduces the remaining balance of your loan. In the early years of a mortgage, this amount is small but grows over time.
Interest: The fee the lender charges for lending you money. With an amortization schedule, you pay more interest upfront.
Taxes: Property taxes assessed by your local government. Lenders typically collect this monthly and hold it in an escrow account to pay the bill when it's due.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is usually collected monthly into escrow.
How Down Payments Affect Your Loan
Your down payment significantly impacts your monthly obligations. A larger down payment reduces the principal loan amount (the amount you need to borrow), which lowers your monthly Principal & Interest (P&I) payment. Additionally, if you put down less than 20%, you may be required to pay Private Mortgage Insurance (PMI), which increases costs until you build enough equity.
Interest Rates and Affordability
Even a small fluctuation in interest rates can drastically change the total cost of your home. A 1% increase in interest rate can add hundreds of dollars to a monthly payment and tens of thousands of dollars in total interest paid over a 30-year term. Use the calculator above to scenario-test different rates to see what you can truly afford.
function calculateMortgage() {
// 1. Retrieve Input Values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = parseFloat(document.getElementById('loanTerm').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualInsurance = parseFloat(document.getElementById('homeInsurance').value);
var monthlyHOA = parseFloat(document.getElementById('hoaFees').value);
// 2. Validate Inputs
if (isNaN(homePrice) || homePrice < 0) homePrice = 0;
if (isNaN(downPayment) || downPayment < 0) downPayment = 0;
if (isNaN(interestRate) || interestRate < 0) interestRate = 0;
if (isNaN(loanTermYears) || loanTermYears <= 0) loanTermYears = 30; // default to 30 if invalid
if (isNaN(annualTax) || annualTax < 0) annualTax = 0;
if (isNaN(annualInsurance) || annualInsurance < 0) annualInsurance = 0;
if (isNaN(monthlyHOA) || monthlyHOA < 0) monthlyHOA = 0;
// 3. Calculate Loan Variables
var principal = homePrice – downPayment;
// Handle case where down payment is greater than home price
if (principal 0) {
if (interestRate === 0) {
// Simple division if interest is 0
monthlyPI = principal / numberOfPayments;
} else {
// Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPI = principal * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
}
// 5. Calculate Monthly Escrow Components
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
// 6. Calculate Total Monthly Payment
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + monthlyHOA;
// 7. Calculate Total Interest Paid
var totalPaymentOverTerm = monthlyPI * numberOfPayments;
var totalInterest = totalPaymentOverTerm – principal;
if (totalInterest < 0) totalInterest = 0;
// 8. Formatting Function for Currency
function formatCurrency(num) {
return new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(num);
}
// 9. Display Results
document.getElementById('totalMonthlyDisplay').innerText = formatCurrency(totalMonthlyPayment);
document.getElementById('loanAmountDisplay').innerText = formatCurrency(principal);
document.getElementById('piDisplay').innerText = formatCurrency(monthlyPI);
document.getElementById('taxDisplay').innerText = formatCurrency(monthlyTax);
document.getElementById('insDisplay').innerText = formatCurrency(monthlyInsurance);
document.getElementById('hoaDisplay').innerText = formatCurrency(monthlyHOA);
document.getElementById('totalInterestDisplay').innerText = formatCurrency(totalInterest);
// Show the results container
document.getElementById('resultsArea').style.display = 'block';
}