#mortgage-calculator-wrapper .calc-header {
background-color: #2c3e50;
color: white;
padding: 20px;
text-align: center;
}
#mortgage-calculator-wrapper .calc-header h2 {
margin: 0;
font-size: 24px;
}
#mortgage-calculator-wrapper .calc-body {
padding: 25px;
display: flex;
flex-wrap: wrap;
gap: 20px;
}
#mortgage-calculator-wrapper .input-group {
flex: 1 1 300px;
display: flex;
flex-direction: column;
gap: 15px;
}
#mortgage-calculator-wrapper .result-group {
flex: 1 1 300px;
background-color: #f8f9fa;
padding: 20px;
border-radius: 8px;
border: 1px solid #dee2e6;
display: flex;
flex-direction: column;
justify-content: center;
}
#mortgage-calculator-wrapper label {
font-weight: 600;
font-size: 14px;
color: #333;
margin-bottom: 5px;
display: block;
}
#mortgage-calculator-wrapper input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
#mortgage-calculator-wrapper input:focus {
border-color: #3498db;
outline: none;
box-shadow: 0 0 5px rgba(52, 152, 219, 0.3);
}
#mortgage-calculator-wrapper button {
background-color: #27ae60;
color: white;
border: none;
padding: 12px 20px;
font-size: 16px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
margin-top: 10px;
width: 100%;
}
#mortgage-calculator-wrapper button:hover {
background-color: #219150;
}
#mortgage-calculator-wrapper .result-row {
display: flex;
justify-content: space-between;
padding: 8px 0;
border-bottom: 1px solid #e9ecef;
font-size: 15px;
}
#mortgage-calculator-wrapper .result-row:last-child {
border-bottom: none;
font-weight: bold;
font-size: 18px;
color: #2c3e50;
margin-top: 10px;
border-top: 2px solid #2c3e50;
padding-top: 15px;
}
#mortgage-calculator-wrapper .article-section {
padding: 25px;
border-top: 1px solid #eee;
background-color: #fff;
color: #444;
line-height: 1.6;
}
#mortgage-calculator-wrapper .article-section h3 {
color: #2c3e50;
margin-top: 20px;
margin-bottom: 10px;
}
#mortgage-calculator-wrapper .article-section p {
margin-bottom: 15px;
}
#mortgage-calculator-wrapper .error-msg {
color: #e74c3c;
font-size: 14px;
display: none;
margin-top: 5px;
}
function calculateMortgage() {
// Get input values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var loanTermYears = parseFloat(document.getElementById('loanTerm').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var propertyTaxYearly = parseFloat(document.getElementById('propertyTax').value);
var homeInsuranceYearly = parseFloat(document.getElementById('homeInsurance').value);
var hoaFeesMonthly = parseFloat(document.getElementById('hoaFees').value);
var errorMsg = document.getElementById('calcError');
// Validate inputs
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) || isNaN(interestRate) ||
homePrice < 0 || downPayment < 0 || loanTermYears <= 0 || interestRate < 0) {
errorMsg.style.display = 'block';
return;
}
errorMsg.style.display = 'none';
// Handle optional fields (treat NaN as 0)
if (isNaN(propertyTaxYearly)) propertyTaxYearly = 0;
if (isNaN(homeInsuranceYearly)) homeInsuranceYearly = 0;
if (isNaN(hoaFeesMonthly)) hoaFeesMonthly = 0;
// Core Calculations
var principal = homePrice – downPayment;
// Avoid negative principal
if (principal < 0) principal = 0;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPrincipalInterest = 0;
// Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
if (interestRate === 0) {
monthlyPrincipalInterest = principal / numberOfPayments;
} else {
var compoundFactor = Math.pow(1 + monthlyInterestRate, numberOfPayments);
monthlyPrincipalInterest = principal * (monthlyInterestRate * compoundFactor) / (compoundFactor – 1);
}
// Monthly Tax and Insurance
var monthlyTax = propertyTaxYearly / 12;
var monthlyInsurance = homeInsuranceYearly / 12;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + hoaFeesMonthly;
// Update UI
document.getElementById('resPrincipalInterest').innerText = '$' + formatMoney(monthlyPrincipalInterest);
document.getElementById('resTax').innerText = '$' + formatMoney(monthlyTax);
document.getElementById('resInsurance').innerText = '$' + formatMoney(monthlyInsurance);
document.getElementById('resHOA').innerText = '$' + formatMoney(hoaFeesMonthly);
document.getElementById('resTotal').innerText = '$' + formatMoney(totalMonthlyPayment);
document.getElementById('resLoanAmount').innerText = '$' + formatMoney(principal);
}
function formatMoney(amount) {
return amount.toLocaleString('en-US', {
minimumFractionDigits: 2,
maximumFractionDigits: 2
});
}
// Initialize calculation on load
window.onload = function() {
// Optional: attach enter key listeners or simple init
// We won't auto-calculate to avoid overwriting placeholders initially,
// but user can click. Or we can run it once:
// calculateMortgage();
};
Mortgage Payment Calculator
Please enter valid positive numbers.
Monthly Breakdown
Principal & Interest:
$1,769.79
Property Tax:
$375.00
Home Insurance:
$100.00
HOA Fees:
$0.00
Total Monthly Payment:
$2,244.79
Total Loan Amount: $280,000
Understanding Your Mortgage Payment
A mortgage is likely the largest financial commitment you will make in your lifetime. Understanding exactly how your monthly payment is calculated is crucial for budgeting and long-term financial health. This calculator breaks down the four main components of a standard mortgage payment: Principal, Interest, Taxes, and Insurance (often referred to as PITI).
How Interest Rates Impact Affordability
Even a small difference in interest rates can significantly affect your monthly payment and the total cost of your loan. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate is roughly $200 per month. Over a 30-year term, that adds up to over $70,000 in extra interest paid.
The Role of Down Payments
Your down payment directly reduces your principal loan amount. A larger down payment (typically 20% or more) not only lowers your monthly principal and interest payments but may also help you avoid Private Mortgage Insurance (PMI), further reducing your monthly obligations.
Estimating Taxes and Insurance
While principal and interest are fixed on a standard mortgage, property taxes and homeowners insurance can fluctuate. It is wise to estimate slightly higher for these costs when budgeting to ensure you are prepared for potential increases in local tax rates or insurance premiums.