.mortgage-calc-wrapper {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
border: 1px solid #e0e0e0;
border-radius: 8px;
background: #ffffff;
box-shadow: 0 4px 12px rgba(0,0,0,0.05);
padding: 30px;
}
.mortgage-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 25px;
}
@media (max-width: 600px) {
.mortgage-calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
color: #333;
font-size: 14px;
}
.input-group input, .input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
.input-group input:focus {
border-color: #0073aa;
outline: none;
}
.calc-btn {
width: 100%;
padding: 15px;
background-color: #0073aa;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #005177;
}
.calc-results {
margin-top: 30px;
padding: 20px;
background-color: #f9f9f9;
border-radius: 6px;
border-left: 5px solid #0073aa;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 15px;
color: #555;
}
.result-row.total {
font-weight: bold;
color: #222;
font-size: 20px;
margin-top: 15px;
padding-top: 15px;
border-top: 1px solid #ddd;
}
.mortgage-article {
margin-top: 40px;
line-height: 1.6;
color: #333;
}
.mortgage-article h2 {
font-size: 24px;
color: #2c3e50;
margin-top: 30px;
margin-bottom: 15px;
}
.mortgage-article h3 {
font-size: 20px;
color: #34495e;
margin-top: 25px;
margin-bottom: 10px;
}
.mortgage-article p {
margin-bottom: 15px;
}
.mortgage-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.mortgage-article li {
margin-bottom: 8px;
}
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 loanTermYears = parseInt(document.getElementById('loanTerm').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualInsurance = parseFloat(document.getElementById('homeInsurance').value);
// Basic Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTermYears)) {
alert("Please enter valid numbers for Home Price, Down Payment, and Interest Rate.");
return;
}
// Defaults for optional fields if empty/NaN
if (isNaN(annualTax)) annualTax = 0;
if (isNaN(annualInsurance)) annualInsurance = 0;
// Calculations
var principal = homePrice – downPayment;
if (principal <= 0) {
alert("Down payment cannot be greater than or equal to the home price.");
return;
}
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
// Monthly Principal & Interest (M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ])
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance;
var totalInterest = (monthlyPI * numberOfPayments) – principal;
// Update DOM
document.getElementById('resPI').innerText = "$" + monthlyPI.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resTax').innerText = "$" + monthlyTax.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resIns').innerText = "$" + monthlyInsurance.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resTotal').innerText = "$" + totalMonthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resTotalInterest').innerText = "$" + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Show results container
document.getElementById('resultsArea').style.display = 'block';
}
Advanced Mortgage Calculator
30 Years
20 Years
15 Years
10 Years
Monthly Payment Breakdown
Principal & Interest:
$0.00
Property Tax:
$0.00
Home Insurance:
$0.00
Total Monthly Payment:
$0.00
Total Interest Paid over Loan Life: $0.00
Understanding Your Mortgage Calculation
Purchasing a home is likely the largest financial commitment you will make in your lifetime. Understanding how your monthly mortgage payment is calculated is essential for budgeting and long-term financial planning. This calculator breaks down the "PITI" components: Principal, Interest, Taxes, and Insurance.
The Components of Your Monthly Payment
- Principal: The portion of your payment that goes toward paying down the money you borrowed. In the early years of a mortgage, this amount is small, but it grows over time.
- Interest: The fee you pay to the lender for borrowing the money. Higher interest rates significantly increase your monthly payment and the total cost of the loan.
- Property Taxes: Assessed by your local government to fund public services. This calculator estimates the monthly set-aside required for these annual bills.
- Homeowners Insurance: Protects your property against damage. Lenders typically require this to be paid monthly via an escrow account.
How Interest Rates Impact Affordability
Even a small difference in interest rates can have a massive impact on your purchasing power. For example, on a $350,000 loan, the difference between a 6% and a 7% interest rate can change your monthly payment by over $200 and cost you tens of thousands of dollars in additional interest over the life of a 30-year loan.
Why the Down Payment Matters
Your down payment reduces the principal loan amount immediately. A larger down payment (typically 20% or more) not only lowers your monthly Principal & Interest payment but may also help you avoid Private Mortgage Insurance (PMI), a fee lenders charge borrowers with less equity.
Use the tool above to experiment with different scenarios. Try adjusting the Loan Term to see how a 15-year mortgage increases monthly payments but drastically reduces the total interest paid.