.mortgage-calculator-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
}
.mc-header {
text-align: center;
margin-bottom: 30px;
}
.mc-header h2 {
margin: 0;
color: #2c3e50;
}
.mc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.mc-grid {
grid-template-columns: 1fr;
}
}
.mc-input-group {
margin-bottom: 15px;
}
.mc-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #555;
font-size: 14px;
}
.mc-input-group input, .mc-input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.mc-input-group input:focus {
border-color: #3498db;
outline: none;
}
.mc-button-container {
grid-column: 1 / -1;
text-align: center;
margin-top: 10px;
}
.mc-btn {
background-color: #2ecc71;
color: white;
border: none;
padding: 12px 30px;
font-size: 18px;
border-radius: 5px;
cursor: pointer;
transition: background-color 0.3s;
}
.mc-btn:hover {
background-color: #27ae60;
}
.mc-results {
grid-column: 1 / -1;
margin-top: 25px;
background: white;
padding: 20px;
border-radius: 6px;
box-shadow: 0 2px 5px rgba(0,0,0,0.05);
display: none;
}
.mc-result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.mc-result-row:last-child {
border-bottom: none;
font-weight: bold;
font-size: 1.2em;
color: #2c3e50;
margin-top: 10px;
border-top: 2px solid #eee;
}
.mc-article {
margin-top: 40px;
line-height: 1.6;
color: #333;
}
.mc-article h3 {
color: #2c3e50;
margin-top: 25px;
}
.error-msg {
color: red;
text-align: center;
display: none;
margin-top: 10px;
}
function calculateMortgage() {
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 errorMsg = document.getElementById('errorMsg');
var resultBox = document.getElementById('result');
// Default values for tax/insurance if left empty
if (isNaN(propertyTax)) propertyTax = 0;
if (isNaN(homeInsurance)) homeInsurance = 0;
// Strict check for core loan variables
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm)) {
errorMsg.style.display = 'block';
resultBox.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
var principal = homePrice – downPayment;
if (principal <= 0) {
errorMsg.innerHTML = "Down payment cannot be greater than or equal to Home Price.";
errorMsg.style.display = 'block';
resultBox.style.display = 'none';
return;
}
// Calculations
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
// Monthly Principal & Interest Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
var x = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPI = (principal * x * monthlyRate) / (x – 1);
}
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
// Update DOM
document.getElementById('resPI').innerHTML = formatter.format(monthlyPI);
document.getElementById('resTax').innerHTML = formatter.format(monthlyTax);
document.getElementById('resIns').innerHTML = formatter.format(monthlyInsurance);
document.getElementById('resTotal').innerHTML = formatter.format(totalMonthly);
document.getElementById('resLoanAmount').innerHTML = formatter.format(principal);
resultBox.style.display = 'block';
}
Mortgage Payment Calculator
Estimate your monthly house payments including tax and insurance.
30 Years
20 Years
15 Years
10 Years
Payment Breakdown
Principal & Interest:
$0.00
Monthly Property Tax:
$0.00
Monthly Home Insurance:
$0.00
Total Monthly Payment:
$0.00
Loan Amount: $0.00
How to Use This Mortgage Calculator
Understanding your potential monthly mortgage payment is the first step in the home buying process. This calculator helps you estimate your monthly financial commitment by factoring in the key components of a home loan.
Understanding the Inputs
- Home Price: The total purchase price of the real estate property.
- Down Payment: The cash amount you pay upfront. A higher down payment reduces the principal loan amount and your monthly payments.
- Interest Rate: The annual percentage rate (APR) charged by the lender. This varies based on your credit score and current market conditions.
- Loan Term: The duration of the loan. 30-year terms generally have lower monthly payments but higher total interest costs compared to 15-year terms.
- Property Tax & Insurance: These are "escrow" costs often bundled into your monthly payment by lenders.
How is the Monthly Payment Calculated?
The core of the calculation uses the standard amortization formula to determine Principal and Interest (P&I). However, the "real" cost of owning a home includes PITI (Principal, Interest, Taxes, and Insurance).
The Formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
Where M is total monthly payment, P is the principal loan amount, i is the monthly interest rate, and n is the number of payments.
Why Taxes and Insurance Matter
Many simple calculators overlook property taxes and homeowners insurance, which can significantly increase your monthly outlay. In many US states, property taxes can add $300 to $1,000+ per month to your bill. Using a calculator that includes these variables ensures you don't underestimate your budget.