Mortgage Payment Calculator
.calculator-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 20px;
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.calc-header {
text-align: center;
margin-bottom: 30px;
}
.calc-header h2 {
color: #2c3e50;
margin-bottom: 10px;
}
.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: 5px;
font-weight: 600;
color: #34495e;
font-size: 0.9em;
}
.input-wrapper {
position: relative;
}
.input-wrapper input {
width: 100%;
padding: 10px 10px 10px 15px;
font-size: 16px;
border: 1px solid #bdc3c7;
border-radius: 4px;
box-sizing: border-box;
}
.input-wrapper input:focus {
border-color: #3498db;
outline: none;
box-shadow: 0 0 0 2px rgba(52, 152, 219, 0.2);
}
.currency-symbol, .percent-symbol {
position: absolute;
color: #7f8c8d;
top: 50%;
transform: translateY(-50%);
}
.currency-symbol { left: 8px; }
.percent-symbol { right: 25px; } /* Adjust for number spinner */
.calc-btn {
grid-column: 1 / -1;
background-color: #27ae60;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background 0.3s;
width: 100%;
margin-top: 10px;
}
.calc-btn:hover {
background-color: #219150;
}
.results-section {
margin-top: 30px;
background-color: #f8f9fa;
padding: 20px;
border-radius: 8px;
border-left: 5px solid #3498db;
display: none; /* Hidden by default */
}
.results-section.visible {
display: block;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #e9ecef;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
color: #555;
}
.result-value {
font-weight: bold;
color: #2c3e50;
}
.big-result {
font-size: 1.5em;
color: #27ae60;
}
/* SEO Content Styling */
.seo-content {
max-width: 800px;
margin: 40px auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
line-height: 1.6;
color: #333;
}
.seo-content h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 30px;
}
.seo-content h3 {
color: #34495e;
margin-top: 25px;
}
.seo-content p {
margin-bottom: 15px;
}
.seo-content ul {
margin-bottom: 15px;
padding-left: 20px;
}
.seo-content li {
margin-bottom: 8px;
}
.formula-box {
background: #f1f2f6;
padding: 15px;
border-radius: 5px;
font-family: monospace;
margin: 15px 0;
text-align: center;
border: 1px solid #dcdde1;
}
Monthly Breakdown
Principal & Interest:
$0.00
Property Tax (Monthly):
$0.00
Home Insurance (Monthly):
$0.00
Total Monthly Payment:
$0.00
Total Interest Paid over Loan Life: $0.00
function calculateMortgage() {
// 1. Get Input Values
var price = parseFloat(document.getElementById('homePrice').value);
var down = parseFloat(document.getElementById('downPayment').value);
var rateVal = parseFloat(document.getElementById('interestRate').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var tax = parseFloat(document.getElementById('annualTax').value);
var insurance = parseFloat(document.getElementById('annualInsurance').value);
// 2. Validate Inputs
if (isNaN(price) || isNaN(down) || isNaN(rateVal) || isNaN(years)) {
alert("Please enter valid numbers for Home Price, Down Payment, Interest Rate, and Term.");
return;
}
// Handle optional fields as 0 if empty
if (isNaN(tax)) tax = 0;
if (isNaN(insurance)) insurance = 0;
// 3. Calculation Logic
var principal = price – down;
// Prevent negative principal
if (principal <= 0) {
alert("Down payment cannot be greater than or equal to the home price.");
return;
}
var monthlyRate = (rateVal / 100) / 12;
var numberOfPayments = years * 12;
var monthlyPI = 0;
// Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
if (rateVal === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var monthlyTax = tax / 12;
var monthlyIns = insurance / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns;
// Total Cost Calculation
var totalCost = monthlyPI * numberOfPayments;
var totalInterest = totalCost – principal;
// 4. Formatting Output (USD)
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// 5. Display Results
document.getElementById('resPI').innerHTML = formatter.format(monthlyPI);
document.getElementById('resTax').innerHTML = formatter.format(monthlyTax);
document.getElementById('resIns').innerHTML = formatter.format(monthlyIns);
document.getElementById('resTotal').innerHTML = formatter.format(totalMonthly);
document.getElementById('resTotalInterest').innerHTML = formatter.format(totalInterest);
// Show result section
document.getElementById('resultSection').classList.add('visible');
}
Understanding Your Mortgage Calculation
Buying a home is often the largest financial decision a person makes. Using a Mortgage Payment Calculator allows prospective buyers to assess affordability by breaking down the loan into monthly obligations. A standard mortgage payment isn't just the repayment of the loan; it often includes interest, taxes, and insurance (collectively known as PITI).
How the Mortgage Formula Works
Behind the scenes, this calculator uses the standard amortization formula to determine the monthly principal and interest payment:
M = P [ i(1 + i)n ] / [ (1 + i)n – 1 ]
Where:
- M = Total monthly payment
- P = Principal loan amount (Home Price minus Down Payment)
- i = Monthly interest rate (Annual rate divided by 12)
- n = Total number of payments (Loan term in years multiplied by 12)
Components of a Mortgage Payment (PITI)
When budgeting for a home, it is crucial to understand that the sticker price of the house is only one factor. The acronym PITI describes the four main components of a monthly mortgage bill:
- Principal: The portion of your payment that goes toward reducing the loan balance. In the early years of a loan, this amount is small, but it increases over time.
- Interest: The fee charged by the lender for borrowing money. Initially, the majority of your payment goes toward interest.
- Taxes: Property taxes assessed by your local government. These are often collected by the lender in an escrow account and paid annually on your behalf.
- Insurance: Homeowners insurance protects the property against damage. Like taxes, this is usually bundled into your monthly payment.
How Interest Rates Affect Buying Power
Even a small change in interest rates can significantly impact your monthly payment and total purchasing power. For example, on a $300,000 loan, a 1% increase in interest rate can raise the monthly payment by hundreds of dollars and increase the total interest paid over 30 years by tens of thousands of dollars.
It is advisable to check current market rates and input them into the calculator above to get the most accurate estimate for your specific financial situation.
What About PMI?
If your down payment is less than 20% of the home's purchase price, lenders typically require Private Mortgage Insurance (PMI). While this calculator estimates PITI, be aware that PMI can add an additional 0.5% to 1% of the loan amount annually to your costs until you reach 20% equity.