Please enter valid positive numbers for all fields.
Estimated Monthly Payment
$0.00
Principal & Interest:$0.00
Property Tax (Monthly):$0.00
Home Insurance (Monthly):$0.00
HOA Fees:$0.00
Loan Amount:$0.00
Total Interest Paid:$0.00
Payoff Date:–
How to Calculate Your Mortgage Payment
Understanding the true cost of homeownership is crucial before signing on the dotted line. This Mortgage Payment Calculator helps you estimate your monthly financial commitment by breaking down the four major components of a mortgage payment, often referred to as PITI (Principal, Interest, Taxes, and Insurance).
Key Factors Affecting Your Mortgage
Principal: This is the money you borrowed to buy the home. A portion of your monthly payment goes toward reducing this balance.
Interest: The cost of borrowing money from the lender. In the early years of a mortgage, a significant percentage of your payment goes toward interest rather than principal.
Escrow Costs (Taxes & Insurance): Most lenders require you to pay a portion of your annual property taxes and homeowner's insurance premiums each month. These funds are held in an escrow account and paid on your behalf when due.
HOA Fees: If you are buying a condo or a home in a planned community, Homeowners Association fees are usually paid separately, but we include them here to give you a complete picture of your monthly housing expense.
Why Your Interest Rate Matters
Even a small difference in interest rates can have a massive impact on your monthly payment and the total cost of the loan over time. For example, on a $300,000 loan, a 1% increase in interest rate can increase your monthly payment by hundreds of dollars and your total interest paid by tens of thousands over a 30-year term. Use the "Interest Rate" field above to simulate different scenarios and see how refinancing or shopping for a better rate could save you money.
30-Year vs. 15-Year Mortgages
Adjusting the "Loan Term" in the calculator allows you to compare the most common loan types. A 30-year fixed-rate mortgage typically offers lower monthly payments, making homes more affordable month-to-month. However, a 15-year mortgage usually comes with a lower interest rate and significantly reduces the total interest paid over the life of the loan, though the monthly payments will be higher.
function calculateMortgage() {
// 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 propertyTax = parseFloat(document.getElementById('propertyTax').value);
var homeInsurance = parseFloat(document.getElementById('homeInsurance').value);
var hoaFees = parseFloat(document.getElementById('hoaFees').value);
// Error handling elements
var errorMsg = document.getElementById('errorMsg');
var resultsArea = document.getElementById('results');
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) ||
isNaN(propertyTax) || isNaN(homeInsurance) || isNaN(hoaFees) ||
homePrice < 0 || downPayment < 0 || interestRate < 0 || loanTerm = home price
if (loanAmount <= 0) {
loanAmount = 0;
var monthlyPI = 0;
var totalInterest = 0;
} else {
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
// Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
if (interestRate === 0) {
var monthlyPI = loanAmount / numberOfPayments;
} else {
var monthlyPI = (loanAmount * monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var totalPaymentOverTime = monthlyPI * numberOfPayments;
var totalInterest = totalPaymentOverTime – loanAmount;
}
// Monthly Tax and Insurance
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + hoaFees;
// Calculate Payoff Date
var today = new Date();
var payoffYear = today.getFullYear() + loanTerm;
var payoffMonth = today.toLocaleString('default', { month: 'short' });
var payoffDateString = payoffMonth + " " + payoffYear;
// Formatting Helper
function formatCurrency(num) {
return '$' + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
// Display Results
document.getElementById('monthlyPaymentResult').innerHTML = formatCurrency(totalMonthlyPayment);
document.getElementById('piResult').innerHTML = formatCurrency(monthlyPI);
document.getElementById('taxResult').innerHTML = formatCurrency(monthlyTax);
document.getElementById('insResult').innerHTML = formatCurrency(monthlyInsurance);
document.getElementById('hoaResult').innerHTML = formatCurrency(hoaFees);
document.getElementById('loanAmountResult').innerHTML = formatCurrency(loanAmount);
document.getElementById('totalInterestResult').innerHTML = formatCurrency(totalInterest);
document.getElementById('payoffDateResult').innerHTML = payoffDateString;
// Show results area
resultsArea.style.display = 'block';
}