Estimate your monthly payments including principal, interest, taxes, and insurance.
Please enter valid numbers for all fields.
Monthly Payment Breakdown
Principal & Interest:$0.00
Property Taxes:$0.00
Homeowner's Insurance:$0.00
HOA Fees:$0.00
PMI (Est.):$0.00
Total Monthly Payment:$0.00
Loan Summary:
Loan Amount: $0 |
Total Interest Paid: $0
function calculateMortgage() {
// Get Inputs
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTerm = parseFloat(document.getElementById('loanTerm').value);
var propertyTax = parseFloat(document.getElementById('propertyTax').value);
var insurance = parseFloat(document.getElementById('insurance').value);
var hoaFees = parseFloat(document.getElementById('hoaFees').value);
var errorDiv = document.getElementById('error-message');
var resultsDiv = document.getElementById('mortgage-results');
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(propertyTax) || isNaN(insurance) || isNaN(hoaFees)) {
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
errorDiv.style.display = 'none';
// Core Calculation Logic
var principal = homePrice – downPayment;
var r = (interestRate / 100) / 12; // Monthly Interest Rate
var n = loanTerm * 12; // Total Number of Payments
var monthlyPI = 0;
// Handle zero interest rate edge case
if (interestRate === 0) {
monthlyPI = principal / n;
} else {
monthlyPI = principal * ( (r * Math.pow(1 + r, n)) / (Math.pow(1 + r, n) – 1) );
}
// Monthly Components
var monthlyTax = propertyTax / 12;
var monthlyIns = insurance / 12;
// PMI Calculation: Typically required if equity 80%
var pmi = 0;
var equityPercent = (downPayment / homePrice) * 100;
if (equityPercent < 20) {
pmi = (principal * 0.005) / 12;
}
var totalMonthly = monthlyPI + monthlyTax + monthlyIns + hoaFees + pmi;
var totalCost = (monthlyPI * n);
var totalInterest = totalCost – principal;
// Output Results
document.getElementById('res-pi').innerHTML = '$' + monthlyPI.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-tax').innerHTML = '$' + monthlyTax.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-ins').innerHTML = '$' + monthlyIns.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-hoa').innerHTML = '$' + hoaFees.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-pmi').innerHTML = '$' + pmi.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-total').innerHTML = '$' + totalMonthly.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res-loan-amount').innerHTML = '$' + principal.toLocaleString('en-US', {minimumFractionDigits: 0, maximumFractionDigits: 0});
document.getElementById('res-total-interest').innerHTML = '$' + totalInterest.toLocaleString('en-US', {minimumFractionDigits: 0, maximumFractionDigits: 0});
resultsDiv.style.display = 'block';
}
Understanding Your Mortgage Payment
Calculating your mortgage payment is a critical step in the home buying process. This Mortgage Payment Calculator helps you estimate your monthly financial commitment by factoring in the Principal, Interest, Taxes, and Insurance (often referred to as PITI).
1. Principal and Interest (P&I)
The largest portion of your payment typically goes toward the loan itself. The Principal pays down the loan balance, while the Interest is the cost of borrowing money from your lender. In the early years of a mortgage, a higher percentage of your payment goes toward interest, while later payments focus more on the principal.
2. Property Taxes and Insurance
Most lenders require you to pay a portion of your annual property taxes and homeowner's insurance each month. These funds are held in an escrow account.
Property Tax: Based on your local government's tax rate and the assessed value of your home.
Homeowner's Insurance: Protects your property against damage and liability.
3. Private Mortgage Insurance (PMI)
If your down payment is less than 20% of the home's purchase price, lenders typically require Private Mortgage Insurance. This calculator estimates PMI at a standard rate of 0.5% annually, though your actual rate may vary based on your credit score and loan type.
How Interest Rates Affect Your Buying Power
Even a small change in interest rates can significantly impact your monthly payment and the total interest paid over the life of the loan. Use the calculator above to experiment with different interest rates to see how they affect your budget. Lowering your interest rate by just 1% can save tens of thousands of dollars over a 30-year term.