.calculator-wrapper-v1 {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
background: #fff;
padding: 20px;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}
.calc-header {
text-align: center;
margin-bottom: 30px;
}
.calc-header h2 {
margin: 0 0 10px;
color: #2c3e50;
font-size: 28px;
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #555;
font-size: 14px;
}
.input-wrapper {
position: relative;
}
.input-prefix, .input-suffix {
position: absolute;
top: 50%;
transform: translateY(-50%);
color: #888;
font-size: 14px;
}
.input-prefix { left: 12px; }
.input-suffix { right: 12px; }
.calc-input {
width: 100%;
padding: 12px 12px 12px 25px;
border: 1px solid #ddd;
border-radius: 6px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
.calc-input:focus {
border-color: #3498db;
outline: none;
}
.input-with-suffix {
padding-right: 35px;
}
.calc-btn {
grid-column: 1 / -1;
background: #2980b9;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
transition: background 0.2s;
margin-top: 10px;
width: 100%;
}
.calc-btn:hover {
background: #2471a3;
}
.calc-results {
margin-top: 30px;
background: #f8f9fa;
padding: 25px;
border-radius: 8px;
border-left: 5px solid #27ae60;
display: none;
}
.result-main {
text-align: center;
margin-bottom: 25px;
border-bottom: 1px solid #e0e0e0;
padding-bottom: 20px;
}
.result-label {
font-size: 16px;
color: #7f8c8d;
margin-bottom: 5px;
}
.result-value-lg {
font-size: 36px;
color: #2c3e50;
font-weight: 800;
}
.breakdown-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 15px;
}
.breakdown-item {
display: flex;
justify-content: space-between;
font-size: 14px;
}
.breakdown-item span:first-child {
color: #555;
}
.breakdown-item span:last-child {
font-weight: 700;
color: #2c3e50;
}
.seo-content {
margin-top: 50px;
line-height: 1.6;
color: #333;
}
.seo-content h3 {
color: #2c3e50;
margin-top: 30px;
}
.seo-content ul {
padding-left: 20px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
display: none;
font-size: 14px;
}
Please enter valid positive numbers for all fields.
function calculateMortgage() {
// Get input values
var price = parseFloat(document.getElementById('homePrice').value);
var down = parseFloat(document.getElementById('downPayment').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var taxYear = parseFloat(document.getElementById('propertyTax').value);
var insYear = parseFloat(document.getElementById('homeInsurance').value);
var hoaMonth = parseFloat(document.getElementById('hoaFees').value);
var errorDiv = document.getElementById('errorMsg');
var resultDiv = document.getElementById('resultsArea');
// Validation
if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(years) ||
isNaN(taxYear) || isNaN(insYear) || isNaN(hoaMonth) ||
price < 0 || down < 0 || years <= 0) {
errorDiv.style.display = 'block';
resultDiv.style.display = 'none';
return;
}
errorDiv.style.display = 'none';
// Calculations
var principal = price – down;
if (principal < 0) principal = 0;
var monthlyRate = (rate / 100) / 12;
var numberOfPayments = years * 12;
var monthlyPrincipalInterest = 0;
// Handle 0% interest edge case
if (rate === 0) {
monthlyPrincipalInterest = principal / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
var mathPow = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPrincipalInterest = principal * (monthlyRate * mathPow) / (mathPow – 1);
}
var monthlyTax = taxYear / 12;
var monthlyIns = insYear / 12;
var totalMonthly = monthlyPrincipalInterest + monthlyTax + monthlyIns + hoaMonth;
var totalCostOfLoan = (monthlyPrincipalInterest * numberOfPayments);
var totalInterest = totalCostOfLoan – principal;
// Update DOM
document.getElementById('totalMonthlyPayment').innerHTML = formatCurrency(totalMonthly);
document.getElementById('monthlyPI').innerHTML = formatCurrency(monthlyPrincipalInterest);
document.getElementById('monthlyTax').innerHTML = formatCurrency(monthlyTax);
document.getElementById('monthlyIns').innerHTML = formatCurrency(monthlyIns);
document.getElementById('monthlyHOA').innerHTML = formatCurrency(hoaMonth);
document.getElementById('totalLoanAmount').innerHTML = formatCurrency(principal);
document.getElementById('totalInterestLifetime').innerHTML = formatCurrency(totalInterest);
resultDiv.style.display = 'block';
}
function formatCurrency(num) {
return '$' + num.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
}
How to Calculate Mortgage Payments
Buying a home is one of the most significant financial decisions you will make. Understanding how your monthly mortgage payment is calculated is crucial for budgeting and determining exactly how much house you can afford. This calculator breaks down the four main components of a standard mortgage payment (PITI): Principal, Interest, Taxes, and Insurance.
Components of Your Monthly Payment
- Principal: The portion of your payment that goes toward paying down the loan balance. In the early years of a mortgage, this amount is small, but it grows over time as you pay down the debt.
- Interest: The cost of borrowing money from the lender. This usually makes up the bulk of your payment in the early years of the loan term.
- Property Taxes: Taxes charged by your local government, typically based on the assessed value of your home. These are often collected by the lender in an escrow account and paid annually on your behalf.
- Homeowners Insurance: Insurance that protects your home against damage. Like taxes, this is often paid through an escrow account.
- HOA Fees: If you buy a condo or a home in a planned community, you may have to pay Homeowners Association fees. While usually paid directly to the HOA, factoring them into your monthly budget is essential.
Why the Down Payment Matters
The size of your down payment significantly impacts your monthly mortgage obligation. A larger down payment reduces your Principal Loan Amount, which lowers your monthly P&I (Principal and Interest) payment. Furthermore, if you put down less than 20% of the home's value, lenders often require Private Mortgage Insurance (PMI), which adds an extra cost to your monthly bill until you reach 20% equity.
How Interest Rates Affect Affordability
Even a small difference in interest rates can have a massive impact on the total cost of your loan. For example, on a $300,000 loan over 30 years, a difference of just 1% in the interest rate can change your monthly payment by hundreds of dollars and the total interest paid over the life of the loan by tens of thousands of dollars. Use the calculator above to experiment with different rates to see how they affect your bottom line.
Frequently Asked Questions
What is an escrow account?
An escrow account is a savings account managed by your mortgage servicer. A portion of your monthly payment goes into this account to cover estimated property taxes and insurance premiums when they are due.
Should I choose a 15-year or 30-year term?
A 30-year term offers lower monthly payments, making the home more affordable month-to-month. A 15-year term has higher monthly payments but significantly reduces the total interest you pay over the life of the loan and allows you to build equity faster.