Buying a home is one of the most significant financial decisions you will make. This Mortgage Payment Calculator is designed to give you a clear, comprehensive breakdown of what your monthly financial commitment will look like. Unlike basic calculators that only show principal and interest, this tool includes critical factors like property taxes, home insurance premiums, and Homeowners Association (HOA) fees.
Why is PITI Important?
Mortgage lenders often refer to PITI—Principal, Interest, Taxes, and Insurance. These four components make up your total monthly housing expense. Ignoring taxes and insurance can lead to "payment shock" when the actual bill arrives.
Breakdown of Costs
Principal: The portion of your payment that goes directly toward reducing your loan balance. In the early years of a mortgage, this amount is small but grows over time.
Interest: The cost of borrowing money. With a fixed-rate mortgage, your interest rate stays the same, but the amount of interest you pay decreases as the principal balance drops.
Property Taxes: Assessed by your local government based on the value of your property. These are typically paid annually or semi-annually but are often collected monthly by your lender in an escrow account.
Homeowners Insurance: Protects your home against damage. Like taxes, this is usually broken down into monthly payments and held in escrow.
HOA Fees: If you buy a condo or a home in a planned community, you may owe monthly dues for common area maintenance. These are usually paid directly to the association, not the lender, but they affect your affordability.
How Interest Rates Impact Your Loan
Even a small difference in your interest rate can have a massive impact on your total loan cost. For example, on a $300,000 loan over 30 years, a difference of just 1% in the interest rate can change your monthly payment by hundreds of dollars and your total interest paid by tens of thousands of dollars.
Using This Calculator for Refinancing
You can also use this tool to see if refinancing makes sense. Enter your current home value and loan balance to see how a new interest rate or a shorter loan term (like 15 years) would change your monthly obligation and total interest costs.
Frequently Asked Questions
What is an escrow account?
An escrow account is a savings account managed by your mortgage servicer. A portion of your monthly payment goes into this account to pay for property taxes and insurance premiums when they are due. This ensures you don't default on tax payments or lose insurance coverage.
Does this calculator include PMI?
Private Mortgage Insurance (PMI) is typically required if your down payment is less than 20% of the home price. While this calculator focuses on PITI and HOA, keep in mind that PMI can add 0.5% to 1% of the loan amount annually to your costs until you reach 20% equity.
function calculateMortgage() {
// Get input values
var homePrice = parseFloat(document.getElementById("homePrice").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var loanTermYears = parseInt(document.getElementById("loanTerm").value);
var interestRateYearly = parseFloat(document.getElementById("interestRate").value);
var propertyTaxYearly = parseFloat(document.getElementById("propertyTax").value);
var homeInsuranceYearly = parseFloat(document.getElementById("homeInsurance").value);
var hoaFeesMonthly = parseFloat(document.getElementById("hoaFees").value);
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) || isNaN(interestRateYearly)) {
alert("Please enter valid numbers for Home Price, Down Payment, Term, and Interest Rate.");
return;
}
// 1. Calculate Loan Amount
var loanAmount = homePrice – downPayment;
// Handle case where down payment is greater than price
if (loanAmount <= 0) {
document.getElementById("totalMonthlyDisplay").innerHTML = "$0.00";
document.getElementById("piDisplay").innerHTML = "$0.00";
// Show results anyway for tax/hoa
document.getElementById("resultsSection").style.display = "block";
return;
}
// 2. Monthly Interest Rate and Total Payments
var monthlyInterestRate = (interestRateYearly / 100) / 12;
var totalPayments = loanTermYears * 12;
// 3. Calculate Monthly Principal & Interest (P&I)
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRateYearly === 0) {
monthlyPI = loanAmount / totalPayments;
} else {
var x = Math.pow(1 + monthlyInterestRate, totalPayments);
monthlyPI = (loanAmount * x * monthlyInterestRate) / (x – 1);
}
// 4. Calculate Other Monthly Costs
var monthlyTax = propertyTaxYearly / 12;
var monthlyInsurance = homeInsuranceYearly / 12;
if (isNaN(monthlyTax)) monthlyTax = 0;
if (isNaN(monthlyInsurance)) monthlyInsurance = 0;
if (isNaN(hoaFeesMonthly)) hoaFeesMonthly = 0;
// 5. Total Monthly Payment
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + hoaFeesMonthly;
// 6. Total Loan Stats
var totalPrincipalAndInterest = monthlyPI * totalPayments;
var totalInterestOnly = totalPrincipalAndInterest – loanAmount;
var totalCostOfLoan = totalPrincipalAndInterest + (monthlyTax * totalPayments) + (monthlyInsurance * totalPayments) + (hoaFeesMonthly * totalPayments) + downPayment;
// 7. Format Functions
function formatCurrency(num) {
return "$" + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
// 8. Update DOM
document.getElementById("totalMonthlyDisplay").innerHTML = formatCurrency(totalMonthlyPayment);
document.getElementById("piDisplay").innerHTML = formatCurrency(monthlyPI);
document.getElementById("taxDisplay").innerHTML = formatCurrency(monthlyTax);
document.getElementById("insDisplay").innerHTML = formatCurrency(monthlyInsurance);
document.getElementById("hoaDisplay").innerHTML = formatCurrency(hoaFeesMonthly);
document.getElementById("totalInterestDisplay").innerHTML = formatCurrency(totalInterestOnly);
document.getElementById("totalCostDisplay").innerHTML = formatCurrency(totalCostOfLoan);
// Show results
document.getElementById("resultsSection").style.display = "block";
}