Please enter valid positive numbers for all fields.
Monthly Payment Breakdown
Principal & Interest:$0.00
Property Tax:$0.00
Homeowner's Insurance:$0.00
HOA Fees:$0.00
Total Monthly Payment:$0.00
Loan Amount: $0.00
Total Interest Paid: $0.00
Understanding Your Mortgage Payment
Calculating your monthly mortgage payment is one of the most critical steps in the home buying process. This comprehensive Mortgage Calculator helps you estimate not just your loan repayment, but the true cost of homeownership including taxes, insurance, and HOA fees.
Components of a Mortgage Payment (PITI)
Your monthly payment is typically comprised of four main parts, often referred to by the acronym PITI:
Principal: The portion of your payment that reduces the loan balance. In the early years of a 30-year mortgage, this amount is small but grows over time.
Interest: The fee charged by the lender for borrowing the money. This makes up the majority of your payment in the beginning of the loan term.
Taxes: Property taxes assessed by your local government. These are usually collected by the lender in an escrow account and paid annually.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is often bundled into your monthly payment via 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 $400,000 loan, the difference between a 6% and a 7% interest rate can equate to hundreds of dollars per month and tens of thousands over the life of the loan.
The Impact of Your Down Payment
Putting more money down upfront reduces the principal amount you need to borrow. A down payment of 20% or more typically allows you to avoid Private Mortgage Insurance (PMI), further lowering your monthly costs. If your down payment is less than 20%, lenders usually require PMI to protect their investment until you build sufficient equity.
Using This Calculator
To get the most accurate result, try to find the specific property tax rate for the area you are looking to buy in (often between 1% and 2% of the home value annually) and get a quote for homeowners insurance. Don't forget to include Homeowners Association (HOA) fees if you are buying a condo or a home in a planned community, as these are paid separately from your mortgage but affect your monthly cash flow.
function calculateMortgage() {
// 1. Get Input Values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var propertyTaxYearly = parseFloat(document.getElementById('propertyTax').value);
var insuranceYearly = parseFloat(document.getElementById('homeInsurance').value);
var hoaMonthly = parseFloat(document.getElementById('hoaFees').value);
// 2. Validation
var errorDiv = document.getElementById('error-message');
var resultsDiv = document.getElementById('results-area');
// Check for NaN or negative values. Allow HOA to be 0.
if (isNaN(homePrice) || homePrice <= 0 ||
isNaN(downPayment) || downPayment < 0 ||
isNaN(interestRate) || interestRate < 0 ||
isNaN(loanTerm) || loanTerm <= 0 ||
isNaN(propertyTaxYearly) || propertyTaxYearly < 0 ||
isNaN(insuranceYearly) || insuranceYearly < 0 ||
isNaN(hoaMonthly) || hoaMonthly = homePrice) {
alert("Down payment cannot be greater than or equal to the home price.");
return;
}
errorDiv.style.display = 'none';
// 3. Calculation Logic
var loanAmount = homePrice – downPayment;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
// Principal and Interest (PI)
var monthlyPI = 0;
if (monthlyInterestRate === 0) {
monthlyPI = loanAmount / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPI = (loanAmount * monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) /
(Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
// Monthly Taxes and Insurance
var monthlyTax = propertyTaxYearly / 12;
var monthlyInsurance = insuranceYearly / 12;
// Total Monthly Payment
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance + hoaMonthly;
// Total Interest over life of loan
var totalCost = (monthlyPI * numberOfPayments);
var totalInterest = totalCost – loanAmount;
// 4. Update UI
// Format Currency Helper
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
document.getElementById('res-pi').textContent = formatter.format(monthlyPI);
document.getElementById('res-tax').textContent = formatter.format(monthlyTax);
document.getElementById('res-ins').textContent = formatter.format(monthlyInsurance);
document.getElementById('res-hoa').textContent = formatter.format(hoaMonthly);
document.getElementById('res-total').textContent = formatter.format(totalMonthly);
document.getElementById('res-loan-amount').textContent = formatter.format(loanAmount);
document.getElementById('res-total-interest').textContent = formatter.format(totalInterest);
// Show results
resultsDiv.style.display = 'block';
// Scroll to results on mobile
resultsDiv.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
}