body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-container {
background: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-title {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.form-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.form-grid {
grid-template-columns: 1fr;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 0.9em;
}
.input-group input, .input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #007bff;
outline: none;
}
.btn-container {
grid-column: 1 / -1;
text-align: center;
margin-top: 10px;
}
button.calc-btn {
background-color: #007bff;
color: white;
border: none;
padding: 12px 30px;
font-size: 18px;
border-radius: 5px;
cursor: pointer;
transition: background-color 0.2s;
}
button.calc-btn:hover {
background-color: #0056b3;
}
#results-area {
grid-column: 1 / -1;
background: #fff;
padding: 20px;
border-radius: 6px;
border-left: 5px solid #007bff;
margin-top: 20px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.result-label {
font-weight: 500;
color: #666;
}
.result-value {
font-weight: 700;
color: #2c3e50;
}
.total-payment {
font-size: 1.4em;
color: #007bff;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.article-content p {
margin-bottom: 15px;
}
.article-content ul {
margin-bottom: 20px;
}
.error-msg {
color: red;
font-weight: bold;
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 hoaFees = parseFloat(document.getElementById('hoaFees').value);
var errorMsg = document.getElementById('error-message');
var resultsArea = document.getElementById('results-area');
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm) ||
isNaN(propertyTax) || isNaN(homeInsurance) || isNaN(hoaFees) ||
homePrice < 0 || downPayment < 0 || interestRate < 0) {
errorMsg.style.display = 'block';
resultsArea.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
// Core Calculation
var principal = homePrice – downPayment;
// Handle 0 or negative principal case
if (principal <= 0) {
principal = 0;
}
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPrincipalInterest = 0;
// Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
if (monthlyRate === 0) {
monthlyPrincipalInterest = principal / numberOfPayments;
} else {
monthlyPrincipalInterest = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// Monthly breakdowns
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + hoaFees;
// Formatting Currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Updating DOM
document.getElementById('res-pi').innerHTML = formatter.format(monthlyPrincipalInterest);
document.getElementById('res-tax').innerHTML = formatter.format(monthlyTax);
document.getElementById('res-ins').innerHTML = formatter.format(monthlyInsurance);
document.getElementById('res-hoa').innerHTML = formatter.format(hoaFees);
document.getElementById('res-total').innerHTML = formatter.format(totalMonthlyPayment);
resultsArea.style.display = 'block';
}
Understanding Your Mortgage Payment
Buying a home is one of the largest financial decisions most people make. A mortgage payment isn't just paying back the loan; it usually consists of four main components, often referred to as PITI (Principal, Interest, Taxes, and Insurance). Our mortgage calculator breaks down these costs to give you a realistic estimate of your monthly obligation.
1. Principal and Interest
The core of your mortgage payment is the Principal and Interest. Principal is the money that goes toward paying down the loan balance, building your equity in the home. Interest is the cost of borrowing that money, paid to the lender. In the early years of a 30-year fixed mortgage, the majority of this portion goes toward interest, while in later years, more goes toward the principal.
2. Property Taxes
Local governments collect property taxes to fund public services like schools, police, and road maintenance. Lenders typically collect this amount alongside your mortgage payment, hold it in an escrow account, and pay the tax bill on your behalf when it's due. Property taxes vary significantly by location and are usually calculated as a percentage of your home's assessed value.
3. Homeowners Insurance
Lenders require you to carry homeowners insurance to protect the property against damages like fire or storms. Similar to property taxes, this premium is often divided into 12 monthly installments and included in your total mortgage payment via an escrow account.
4. HOA Fees
If you are buying a condo, townhouse, or a home in a planned community, you may be required to pay Homeowners Association (HOA) fees. These cover common area maintenance, trash removal, and community amenities. While lenders don't always collect this fee (you might pay it directly to the HOA), it is a critical part of your monthly housing budget and effects your debt-to-income ratio.
How Interest Rates Affect Affordability
Even a small change in interest rates can drastically impact your monthly payment and the total interest paid over the life of the loan. For example, on a $300,000 loan, the difference between a 6.0% and a 7.0% interest rate is roughly $200 per month. Using this calculator allows you to test different rate scenarios to see what you can comfortably afford if rates fluctuate.
Frequently Asked Questions
What is Private Mortgage Insurance (PMI)?
If your down payment is less than 20% of the home's value, lenders typically require PMI. This protects the lender if you default. This calculator focuses on PITI and HOA, but you should budget an extra 0.5% to 1% of the loan amount annually if you have a low down payment.
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 paid over the life of the loan and allows you to build equity much faster.
How much house can I afford?
A common rule of thumb is the 28/36 rule: your housing expenses should not exceed 28% of your gross monthly income, and your total debt (including housing) should not exceed 36%. Use the total monthly payment result from this calculator to check against your monthly income.