Mortgage Payment Calculator
body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
margin: 0;
padding: 20px;
background-color: #f4f7f6;
}
.calculator-container {
max-width: 800px;
margin: 0 auto;
background: #fff;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0,0,0,0.1);
overflow: hidden;
border: 1px solid #e0e0e0;
}
.calc-header {
background: #2c3e50;
color: white;
padding: 20px;
text-align: center;
}
.calc-header h2 {
margin: 0;
font-size: 24px;
}
.calc-body {
padding: 30px;
display: flex;
flex-wrap: wrap;
gap: 30px;
}
.input-section {
flex: 1;
min-width: 300px;
}
.result-section {
flex: 1;
min-width: 300px;
background: #f8f9fa;
padding: 20px;
border-radius: 8px;
border: 1px solid #e9ecef;
}
.form-group {
margin-bottom: 20px;
}
.form-group label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #555;
}
.input-wrapper {
position: relative;
}
.input-prefix {
position: absolute;
left: 12px;
top: 50%;
transform: translateY(-50%);
color: #777;
}
.input-suffix {
position: absolute;
right: 12px;
top: 50%;
transform: translateY(-50%);
color: #777;
}
input[type="number"] {
width: 100%;
padding: 12px 12px 12px 30px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
input[type="number"]:focus {
border-color: #3498db;
outline: none;
}
.btn-calculate {
display: block;
width: 100%;
padding: 15px;
background: #3498db;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background 0.3s;
}
.btn-calculate:hover {
background: #2980b9;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 15px;
padding-bottom: 15px;
border-bottom: 1px solid #e0e0e0;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 500;
color: #666;
}
.result-value {
font-weight: 700;
color: #2c3e50;
}
.big-result {
text-align: center;
margin-bottom: 25px;
padding: 15px;
background: #e8f6f3;
border-radius: 6px;
border: 1px solid #d1f2eb;
}
.big-result h3 {
margin: 0 0 10px 0;
color: #16a085;
font-size: 18px;
}
.big-result .amount {
font-size: 36px;
font-weight: 800;
color: #16a085;
}
.seo-content {
max-width: 800px;
margin: 40px auto;
padding: 30px;
background: #fff;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.seo-content h2 {
color: #2c3e50;
margin-top: 30px;
}
.seo-content h3 {
color: #34495e;
}
.seo-content p {
color: #555;
margin-bottom: 15px;
}
.seo-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.seo-content li {
margin-bottom: 8px;
color: #555;
}
@media (max-width: 768px) {
.calc-body {
flex-direction: column;
}
}
Estimated Monthly Payment
$0.00
Principal & Interest:
$0.00
Property Tax (Monthly):
$0.00
Home Insurance (Monthly):
$0.00
Total Interest Paid:
$0.00
Total Loan Cost:
$0.00
Payoff Date:
–
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);
// Validation
if (isNaN(homePrice) || homePrice <= 0) { alert("Please enter a valid Home Price."); return; }
if (isNaN(downPayment) || downPayment < 0) { downPayment = 0; }
if (isNaN(interestRate) || interestRate < 0) { alert("Please enter a valid Interest Rate."); return; }
if (isNaN(loanTerm) || loanTerm <= 0) { alert("Please enter a valid Loan Term."); return; }
if (isNaN(propertyTax) || propertyTax < 0) { propertyTax = 0; }
if (isNaN(homeInsurance) || homeInsurance < 0) { homeInsurance = 0; }
// Loan Principal
var principal = homePrice – downPayment;
if (principal <= 0) {
alert("Down payment cannot equal or exceed home price for a mortgage calculation.");
return;
}
// Monthly Interest Rate Calculation
var monthlyRate = (interestRate / 100) / 12;
// Total Number of Payments
var numberOfPayments = loanTerm * 12;
// Principal & Interest Calculation Formula: M = P[r(1+r)^n/((1+r)^n)-1)]
var x = Math.pow(1 + monthlyRate, numberOfPayments);
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = (principal * x * monthlyRate) / (x – 1);
}
// Monthly Tax and Insurance
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
// Total Monthly Payment
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance;
// Total Loan Cost metrics
var totalCostOfLoan = (monthlyPI * numberOfPayments);
var totalInterestPaid = totalCostOfLoan – principal;
// Payoff Date
var today = new Date();
var payoffDate = new Date(today.setMonth(today.getMonth() + numberOfPayments));
var options = { month: 'long', year: 'numeric' };
var dateString = payoffDate.toLocaleDateString("en-US", options);
// Formatting Helper
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Display Results
document.getElementById('resultsArea').style.display = 'block';
document.getElementById('totalMonthlyPayment').innerHTML = formatter.format(totalMonthly);
document.getElementById('piPayment').innerHTML = formatter.format(monthlyPI);
document.getElementById('taxPayment').innerHTML = formatter.format(monthlyTax);
document.getElementById('insPayment').innerHTML = formatter.format(monthlyInsurance);
document.getElementById('totalInterest').innerHTML = formatter.format(totalInterestPaid);
document.getElementById('totalCost').innerHTML = formatter.format(totalCostOfLoan + (monthlyTax * numberOfPayments) + (monthlyInsurance * numberOfPayments));
document.getElementById('payoffDate').innerHTML = dateString;
}
// Run once on load to show defaults
window.onload = function() {
calculateMortgage();
};
Understanding Your Mortgage Calculation
Calculating your monthly mortgage payment is a crucial step in the home buying process. This tool allows you to estimate your financial obligations accurately by factoring in principal, interest, taxes, and insurance (PITI). Understanding these components helps in determining "how much house" you can actually afford without stretching your budget.
Key Factors That Influence Your Monthly Payment
- Principal: This is the amount of money you borrow from the lender. It equals the home price minus your down payment. A larger down payment reduces your principal, lowering both your monthly payment and the total interest paid over the life of the loan.
- Interest Rate: The cost of borrowing money, expressed as a percentage. Even a small difference in the interest rate (e.g., 0.5%) can result in saving or spending tens of thousands of dollars over a 30-year term. Rates are determined by your credit score, the economy, and the loan type.
- Loan Term: The duration of the loan. A 30-year term typically offers lower monthly payments but higher total interest costs. A 15-year term has higher monthly payments but significantly reduces the total interest paid.
- Property Taxes & Insurance: Often overlooked in simple calculations, these are usually bundled into your monthly payment through an escrow account. Property taxes vary widely by location, while insurance premiums depend on the property value and coverage level.
Amortization Explained
Mortgage loans typically use an amortization schedule. In the early years of your loan term, the majority of your payment goes toward interest, with only a small fraction reducing the principal balance. As time progresses, this shifts; towards the end of the loan term, most of your payment goes toward the principal. Using this calculator helps you visualize the total cost of the loan, including the substantial amount paid in interest.
How to Lower Your Monthly Payments
If the calculated payment is higher than your budget allows, consider these strategies:
- Increase your down payment to lower the principal amount.
- Shop around for a lower interest rate or buy "points" to reduce the rate.
- Opt for a longer loan term (though this increases total interest paid).
- Look for homes in areas with lower property tax rates.
Note: This calculator provides estimates for educational purposes. Final loan terms will depend on your lender and specific financial situation.