#mortgage-calc-wrapper .calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 25px;
}
#mortgage-calc-wrapper .input-group {
display: flex;
flex-direction: column;
}
#mortgage-calc-wrapper label {
font-weight: 600;
margin-bottom: 8px;
color: #333;
font-size: 14px;
}
#mortgage-calc-wrapper input {
padding: 12px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
transition: border-color 0.3s;
}
#mortgage-calc-wrapper input:focus {
border-color: #0073aa;
outline: none;
}
#mortgage-calc-wrapper .calc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
}
#mortgage-calc-wrapper .calc-btn:hover {
background-color: #005177;
}
#mortgage-calc-wrapper .results-box {
background-color: #f7f9fc;
padding: 25px;
border-radius: 6px;
border-left: 5px solid #0073aa;
margin-top: 30px;
display: none;
}
#mortgage-calc-wrapper .result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #e0e0e0;
}
#mortgage-calc-wrapper .result-row.total {
border-bottom: none;
font-size: 1.2em;
font-weight: 800;
color: #0073aa;
margin-top: 10px;
padding-top: 10px;
border-top: 2px solid #ddd;
}
#mortgage-calc-wrapper .seo-content {
margin-top: 40px;
line-height: 1.6;
color: #444;
}
#mortgage-calc-wrapper h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
#mortgage-calc-wrapper h3 {
color: #34495e;
margin-top: 25px;
}
@media (max-width: 600px) {
#mortgage-calc-wrapper .calc-grid {
grid-template-columns: 1fr;
}
}
Payment Breakdown
Principal & Interest:
$0.00
Property Taxes (Monthly):
$0.00
Home Insurance (Monthly):
$0.00
Total Monthly Payment:
$0.00
Total Interest Over Loan Life: $0.00
Understanding Your Mortgage Calculation
Purchasing a home is one of the most significant financial decisions you will make. This Mortgage Payment Calculator is designed to help you understand exactly what your monthly financial commitment will look like. Unlike basic calculators that only show principal and interest, this tool factors in property taxes and homeowners insurance, which are critical components of your "PITI" (Principal, Interest, Taxes, Insurance) payment.
How the Monthly Payment is Calculated
The core of your mortgage payment is determined by the amortization formula. This mathematical equation ensures that your payments are spread evenly over the life of the loan (typically 15 or 30 years). In the early years, a larger portion of your payment goes toward interest, while in later years, more goes toward the principal balance.
The formula depends heavily on three factors:
- Loan Amount: This is the Home Price minus your Down Payment.
- Interest Rate: The annual cost of borrowing money. Even a small difference (e.g., 0.5%) can save or cost you tens of thousands of dollars over the life of the loan.
- Loan Term: A 30-year term offers lower monthly payments but higher total interest costs compared to a 15-year term.
The Impact of Taxes and Insurance
Many first-time homebuyers are surprised when their actual monthly bill is higher than the quoted mortgage rate. This is due to escrow costs. Lenders often collect 1/12th of your estimated annual property taxes and homeowners insurance premiums each month, holding them in an escrow account to pay the bills when they are due. As shown in the calculation results above, these additional costs can add several hundred dollars to your monthly obligation.
Why the Down Payment Matters
Your down payment directly influences your loan-to-value (LTV) ratio. A larger down payment reduces the principal loan amount, which lowers both your monthly P&I payment and the total interest paid over time. Additionally, if you put down less than 20%, you may be required to pay Private Mortgage Insurance (PMI), which would further increase your monthly costs (note: this calculator focuses on standard PITI; be sure to ask your lender about PMI if your down payment is low).
function calculateMortgagePayment() {
// 1. Get Input Values
var price = document.getElementById('mc_home_price').value;
var down = document.getElementById('mc_down_payment').value;
var rate = document.getElementById('mc_interest_rate').value;
var term = document.getElementById('mc_loan_term').value;
var taxYear = document.getElementById('mc_property_tax').value;
var insYear = document.getElementById('mc_insurance').value;
// 2. Validate Inputs
if (price === "" || down === "" || rate === "" || term === "") {
alert("Please fill in all required fields (Price, Down Payment, Rate, Term).");
return;
}
var homePrice = parseFloat(price);
var downPayment = parseFloat(down);
var interestRate = parseFloat(rate);
var years = parseFloat(term);
var annualTax = (taxYear === "") ? 0 : parseFloat(taxYear);
var annualIns = (insYear === "") ? 0 : parseFloat(insYear);
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(years)) {
alert("Please enter valid numbers.");
return;
}
// 3. Perform Calculations
var principal = homePrice – downPayment;
// Handle edge case where down payment >= home price
if (principal <= 0) {
document.getElementById('res_pi').innerHTML = "$0.00";
document.getElementById('res_tax').innerHTML = "$" + (annualTax / 12).toFixed(2);
document.getElementById('res_ins').innerHTML = "$" + (annualIns / 12).toFixed(2);
document.getElementById('res_total').innerHTML = "$" + ((annualTax + annualIns) / 12).toFixed(2);
document.getElementById('res_total_interest').innerHTML = "$0.00";
document.getElementById('mc_results').style.display = "block";
return;
}
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = years * 12;
// Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
var x = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPI = (principal * x * monthlyRate) / (x – 1);
}
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns;
var totalInterest = (monthlyPI * numberOfPayments) – principal;
// 4. Update UI
// Format numbers with commas
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
});
document.getElementById('res_pi').innerHTML = formatter.format(monthlyPI);
document.getElementById('res_tax').innerHTML = formatter.format(monthlyTax);
document.getElementById('res_ins').innerHTML = formatter.format(monthlyIns);
document.getElementById('res_total').innerHTML = formatter.format(totalMonthly);
document.getElementById('res_total_interest').innerHTML = formatter.format(totalInterest);
// Show results
document.getElementById('mc_results').style.display = "block";
}