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.mc-col { flex: 1; min-width: 250px; }
.mc-label { display: block; font-weight: 600; margin-bottom: 8px; color: #333; }
.mc-input { width: 100%; padding: 12px; border: 1px solid #ddd; border-radius: 4px; font-size: 16px; box-sizing: border-box; }
.mc-input:focus { border-color: #007bff; outline: none; box-shadow: 0 0 0 2px rgba(0,123,255,0.25); }
.mc-btn { width: 100%; padding: 14px; background-color: #007bff; color: white; border: none; border-radius: 4px; font-size: 18px; font-weight: bold; cursor: pointer; transition: background 0.2s; }
.mc-btn:hover { background-color: #0056b3; }
.mc-result-box { background: #f8f9fa; border: 1px solid #e9ecef; border-radius: 6px; padding: 20px; margin-top: 25px; }
.mc-result-row { display: flex; justify-content: space-between; margin-bottom: 10px; font-size: 16px; color: #555; }
.mc-result-row.total { font-size: 24px; font-weight: 800; color: #28a745; margin-top: 15px; padding-top: 15px; border-top: 2px solid #ddd; }
.mc-error { color: #dc3545; display: none; margin-top: 10px; font-weight: 600; }
.mc-article h2 { color: #2c3e50; margin-top: 40px; }
.mc-article h3 { color: #34495e; margin-top: 25px; }
.mc-article p { line-height: 1.6; color: #444; margin-bottom: 15px; }
.mc-article ul { margin-bottom: 15px; padding-left: 20px; }
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Please enter valid numeric values greater than zero.
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 homeInsurance = parseFloat(document.getElementById('homeInsurance').value);
var hoaFees = parseFloat(document.getElementById('hoaFees').value);
// Validation
var errorDiv = document.getElementById('mcError');
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) || isNaN(propertyTax) || isNaN(homeInsurance) || isNaN(hoaFees)) {
errorDiv.style.display = 'block';
document.getElementById('resultSection').style.display = 'none';
return;
}
if (homePrice <= 0 || loanTerm <= 0) {
errorDiv.style.display = 'block';
return;
}
errorDiv.style.display = 'none';
// Calculations
var loanAmount = homePrice – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPI = 0;
// Handle 0% interest case
if (interestRate === 0) {
monthlyPI = loanAmount / numberOfPayments;
} else {
monthlyPI = (loanAmount * monthlyRate) / (1 – Math.pow(1 + monthlyRate, -numberOfPayments));
}
var monthlyTax = propertyTax / 12;
var monthlyIns = homeInsurance / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns + hoaFees;
var totalCost = (monthlyPI * numberOfPayments);
var totalInterest = totalCost – loanAmount;
// Formatter
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Update DOM
document.getElementById('resPI').innerText = formatter.format(monthlyPI);
document.getElementById('resTax').innerText = formatter.format(monthlyTax);
document.getElementById('resIns').innerText = formatter.format(monthlyIns);
document.getElementById('resHOA').innerText = formatter.format(hoaFees);
document.getElementById('resTotal').innerText = formatter.format(totalMonthly);
document.getElementById('resLoanAmount').innerText = formatter.format(loanAmount);
document.getElementById('resTotalInterest').innerText = formatter.format(totalInterest);
document.getElementById('resultSection').style.display = 'block';
}
Understanding Your Monthly Mortgage Payment (PITI)
Calculating a mortgage payment is about more than just repaying the loan. A comprehensive calculation involves four key components, often referred to as PITI: Principal, Interest, Taxes, and Insurance.
- Principal: The portion of your payment that reduces the loan balance.
- Interest: The cost of borrowing money, determined by your interest rate.
- Taxes: Property taxes assessed by your local government, typically paid annually but divided into monthly escrow payments.
- Insurance: Homeowners insurance to protect the property, also usually paid via escrow.
How Down Payment Affects Your Loan
The size of your down payment significantly impacts your monthly obligations. A larger down payment reduces the principal loan amount, which directly lowers your monthly Principal & Interest (P&I) payment. Additionally, if you put down less than 20%, you may be required to pay Private Mortgage Insurance (PMI), which would further increase your monthly costs (note: this calculator focuses on standard PITI; be sure to ask your lender about PMI).
The Impact of Interest Rates and Loan Term
Even a small difference in the interest rate can result in thousands of dollars of savings—or extra costs—over the life of a loan. Similarly, the loan term plays a vital role. A 15-year term usually has a lower interest rate and significantly lower total interest costs, but requires a much higher monthly payment compared to a standard 30-year term.
Why Include HOA Fees?
If you are buying a condo or a home in a planned community, Homeowners Association (HOA) fees are a mandatory monthly expense. While they aren't part of the loan itself, lenders factor them into your Debt-to-Income (DTI) ratio to determine if you can afford the home. Including them in this calculator gives you a true picture of your "out-the-door" monthly housing expense.
How to Use This Calculator
Simply enter the purchase price of the home, your planned down payment, the current interest rate, and the loan duration. Don't forget to estimate annual property taxes and insurance premiums, as these can add several hundred dollars to your monthly bill. Click "Calculate" to see a breakdown of where your money goes every month.