Estimate your monthly payments including tax and insurance.
Please enter valid positive numbers for all fields.
Estimated Monthly Payment
$0.00
Principal & Interest:$0.00
Property Tax:$0.00
Home Insurance:$0.00
HOA Fees:$0.00
Total Loan Amount:$0.00
Total Interest Paid:$0.00
Understanding Your Mortgage Calculation
Buying a home is one of the most significant financial decisions you will make. Using a mortgage calculator is an essential step in the planning process. It allows you to estimate your monthly financial commitment, ensuring you choose a property that fits your budget. This calculator breaks down not just the loan repayment, but also the "hidden" costs like property taxes, insurance, and HOA fees.
How the Mortgage Formula Works
The core of a mortgage payment is calculated using a standard amortization formula. This determines the fixed monthly payment required to pay off the loan principal and interest over a set term (usually 15 or 30 years). The formula considers:
Principal (P): The home price minus your down payment. This is the amount you actually borrow.
Interest Rate (r): The annual percentage rate charged by the lender. In the calculation, this is divided by 12 to get the monthly rate.
Number of Payments (n): The total number of months in the loan term (e.g., 30 years × 12 months = 360 payments).
The PITI Components
Your monthly check to the bank often includes more than just the loan repayment. This is commonly referred to as PITI:
Principal: The portion of your payment that reduces the loan balance.
Interest: The cost of borrowing money. In the early years of a mortgage, a large percentage of your payment goes toward interest.
Taxes: Property taxes assessed by your local government. These are often collected by the lender in an escrow account and paid annually on your behalf.
Insurance: Homeowners insurance protects your property against damage. Lenders require this coverage.
Why Your Down Payment Matters
The down payment plays a crucial role in your monthly costs. putting down 20% or more typically helps you avoid Private Mortgage Insurance (PMI), which is an extra fee charged to borrowers with smaller down payments. Furthermore, a larger down payment reduces your principal loan amount, thereby lowering both your monthly payment and the total interest paid over the life of the loan.
Using These Results
Remember that the figures provided here are estimates. Your actual interest rate will depend on your credit score, debt-to-income ratio, and current market conditions. Property taxes and insurance rates also vary significantly by location. Use this tool as a baseline to start conversations with lenders and real estate agents.
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 homeInsuranceAnnual = parseFloat(document.getElementById('homeInsurance').value);
var hoaFeesMonthly = parseFloat(document.getElementById('hoaFees').value);
var errorMsg = document.getElementById('errorMsg');
var resultsSection = document.getElementById('resultsSection');
// 2. Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) ||
isNaN(interestRateAnnual) || isNaN(propertyTaxAnnual) ||
isNaN(homeInsuranceAnnual) || isNaN(hoaFeesMonthly) ||
homePrice < 0 || downPayment < 0 || loanTermYears = home price
if (loanAmount 0) {
if (interestRateAnnual === 0) {
monthlyPrincipalInterest = loanAmount / numberOfPayments;
} else {
var numerator = monthlyInterestRate * Math.pow((1 + monthlyInterestRate), numberOfPayments);
var denominator = Math.pow((1 + monthlyInterestRate), numberOfPayments) – 1;
monthlyPrincipalInterest = loanAmount * (numerator / denominator);
}
}
// Monthly Extras
var monthlyTax = propertyTaxAnnual / 12;
var monthlyInsurance = homeInsuranceAnnual / 12;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + hoaFeesMonthly;
// Total Totals
var totalCostOfLoan = (monthlyPrincipalInterest * numberOfPayments);
var totalInterestPaid = totalCostOfLoan – loanAmount;
// 4. Update UI
resultsSection.style.display = 'block';
document.getElementById('totalMonthlyPayment').innerText = formatCurrency(totalMonthlyPayment);
document.getElementById('piResult').innerText = formatCurrency(monthlyPrincipalInterest);
document.getElementById('taxResult').innerText = formatCurrency(monthlyTax);
document.getElementById('insResult').innerText = formatCurrency(monthlyInsurance);
document.getElementById('hoaResult').innerText = formatCurrency(hoaFeesMonthly);
document.getElementById('loanAmountResult').innerText = formatCurrency(loanAmount);
document.getElementById('totalInterestResult').innerText = formatCurrency(totalInterestPaid);
}
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}