Mortgage Calculator
.mortgage-calc-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
background: #fff;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-grid {
display: flex;
flex-wrap: wrap;
gap: 20px;
}
.calc-col {
flex: 1;
min-width: 280px;
}
.form-group {
margin-bottom: 20px;
}
.form-group label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #2c3e50;
}
.input-wrapper {
position: relative;
display: flex;
align-items: center;
}
.prefix, .suffix {
background: #f4f4f4;
padding: 12px 15px;
border: 1px solid #ddd;
color: #666;
font-weight: 500;
}
.prefix {
border-right: none;
border-radius: 4px 0 0 4px;
}
.suffix {
border-left: none;
border-radius: 0 4px 4px 0;
}
.form-control {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
font-size: 16px;
border-radius: 0;
}
.form-control:focus {
outline: none;
border-color: #3498db;
background: #fbfbfb;
}
.input-wrapper .form-control:first-child { border-radius: 4px; }
.input-wrapper .prefix + .form-control { border-radius: 0 4px 4px 0; }
.input-wrapper .form-control + .suffix { border-radius: 4px 0 0 4px; } /* Correction handled by order */
.input-wrapper .prefix + .form-control:not(:last-child) { border-radius: 0; }
.btn-calculate {
width: 100%;
background-color: #2980b9;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background-color 0.3s;
margin-top: 10px;
}
.btn-calculate:hover {
background-color: #2471a3;
}
.results-box {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 6px;
padding: 25px;
margin-top: 0;
height: 100%;
box-sizing: border-box;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 12px 0;
border-bottom: 1px solid #e0e0e0;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
color: #555;
font-size: 15px;
}
.result-value {
font-weight: 700;
font-size: 18px;
color: #2c3e50;
}
.main-result {
text-align: center;
padding-bottom: 20px;
border-bottom: 2px solid #3498db;
margin-bottom: 20px;
}
.main-result .label {
display: block;
font-size: 14px;
text-transform: uppercase;
letter-spacing: 1px;
color: #7f8c8d;
margin-bottom: 5px;
}
.main-result .value {
font-size: 42px;
color: #2980b9;
font-weight: 800;
}
.seo-content {
max-width: 800px;
margin: 40px auto 0;
line-height: 1.6;
color: #444;
}
.seo-content h2 {
color: #2c3e50;
margin-top: 30px;
font-size: 24px;
}
.seo-content p {
margin-bottom: 15px;
}
.seo-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.seo-content li {
margin-bottom: 10px;
}
@media (max-width: 600px) {
.calc-col { min-width: 100%; }
.results-box { margin-top: 20px; }
}
Total Monthly Payment
$0.00
Principal & Interest:
$0.00
Property Tax (Monthly):
$0.00
Home Insurance (Monthly):
$0.00
Loan Amount:
$0.00
Total Interest Paid:
$0.00
Understanding Your Mortgage Calculation
Calculating your monthly mortgage payment is a crucial step in the home buying process. This Mortgage Calculator helps you estimate your monthly financial commitment by factoring in the home price, down payment, interest rate, and loan term, along with estimated property taxes and insurance.
How is the Monthly Payment Calculated?
Your total monthly payment is primarily composed of four distinct parts, often referred to as PITI:
- Principal: The portion of the payment that goes toward paying off the money you borrowed.
- Interest: The cost of borrowing money from the lender.
- Taxes: Property taxes assessed by your local government, typically held in escrow and paid by your lender.
- Insurance: Homeowners insurance premiums to protect your property against damage, also typically paid via escrow.
Why the Down Payment Matters
The down payment is the initial upfront payment you make for the home. A larger down payment reduces the principal loan amount, which lowers your monthly payments and the total interest paid over the life of the loan. Typically, if you put down less than 20%, you may also be required to pay Private Mortgage Insurance (PMI), which increases your monthly costs.
Interest Rate Impact
Even a small difference in the interest rate can have a significant impact on your monthly payment and the total cost of the loan. For example, on a $300,000 loan, a 1% difference in interest rate can change your monthly payment by hundreds of dollars and your total interest paid by tens of thousands over a 30-year term.
30-Year vs. 15-Year Term
Choosing a loan term is a balance between affordability and total cost. A 30-year term offers lower monthly payments but results in higher total interest costs. A 15-year term has higher monthly payments but allows you to build equity faster and save significantly on interest.
function calculateMortgage() {
// 1. Get Input Values
var homePrice = parseFloat(document.getElementById("homePrice").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var annualRate = parseFloat(document.getElementById("interestRate").value);
var loanTermYears = parseFloat(document.getElementById("loanTerm").value);
var yearlyTax = parseFloat(document.getElementById("propertyTax").value);
var yearlyIns = parseFloat(document.getElementById("homeInsurance").value);
// 2. Validate Inputs
if (isNaN(homePrice) || homePrice < 0) homePrice = 0;
if (isNaN(downPayment) || downPayment < 0) downPayment = 0;
if (isNaN(annualRate) || annualRate < 0) annualRate = 0;
if (isNaN(loanTermYears) || loanTermYears <= 0) loanTermYears = 30; // Default to 30 if invalid
if (isNaN(yearlyTax) || yearlyTax < 0) yearlyTax = 0;
if (isNaN(yearlyIns) || yearlyIns 0) {
monthlyPrincipalAndInterest = loanAmount / numberOfPayments;
} else {
monthlyPrincipalAndInterest = 0;
}
} else {
// Standard Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var mathPower = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPrincipalAndInterest = loanAmount * (monthlyRate * mathPower) / (mathPower – 1);
}
// Ensure non-negative
if (monthlyPrincipalAndInterest < 0) monthlyPrincipalAndInterest = 0;
var monthlyTax = yearlyTax / 12;
var monthlyIns = yearlyIns / 12;
var totalMonthlyPayment = monthlyPrincipalAndInterest + monthlyTax + monthlyIns;
var totalInterest = (monthlyPrincipalAndInterest * numberOfPayments) – loanAmount;
if (totalInterest < 0) totalInterest = 0; // In case of weird inputs
// 4. Formatting Functions
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// 5. Update HTML Output
document.getElementById("totalMonthlyDisplay").innerHTML = formatter.format(totalMonthlyPayment);
document.getElementById("piDisplay").innerHTML = formatter.format(monthlyPrincipalAndInterest);
document.getElementById("taxDisplay").innerHTML = formatter.format(monthlyTax);
document.getElementById("insDisplay").innerHTML = formatter.format(monthlyIns);
document.getElementById("loanAmountDisplay").innerHTML = formatter.format(loanAmount);
document.getElementById("totalInterestDisplay").innerHTML = formatter.format(totalInterest);
}
// Run calculation once on load to populate default values
calculateMortgage();