.calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calc-container {
background: #f8f9fa;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
margin-bottom: 40px;
border: 1px solid #e9ecef;
}
.calc-title {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
font-size: 24px;
font-weight: 700;
}
.input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 25px;
}
@media (max-width: 600px) {
.input-grid {
grid-template-columns: 1fr;
}
}
.form-group {
display: flex;
flex-direction: column;
}
.form-group label {
font-weight: 600;
margin-bottom: 8px;
font-size: 14px;
color: #555;
}
.form-group input {
padding: 12px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
transition: border-color 0.3s;
}
.form-group input:focus {
border-color: #3498db;
outline: none;
}
.calc-btn {
width: 100%;
padding: 15px;
background-color: #2c3e50;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #34495e;
}
.results-box {
margin-top: 25px;
background: white;
padding: 20px;
border-radius: 4px;
border-left: 5px solid #27ae60;
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;
font-size: 18px;
}
.highlight-value {
color: #27ae60;
font-size: 24px;
}
.seo-content h2 {
color: #2c3e50;
margin-top: 30px;
font-size: 22px;
}
.seo-content p {
margin-bottom: 15px;
font-size: 16px;
}
.seo-content ul {
margin-bottom: 15px;
padding-left: 20px;
}
.seo-content li {
margin-bottom: 8px;
}
.error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
display: none;
font-weight: bold;
}
function calculateMortgagePayment() {
// Get Input Values
var homePrice = document.getElementById('mortgageHomePrice').value;
var downPayment = document.getElementById('mortgageDownPayment').value;
var interestRate = document.getElementById('mortgageInterestRate').value;
var loanTerm = document.getElementById('mortgageLoanTerm').value;
var errorDiv = document.getElementById('mortgageError');
var resultsDiv = document.getElementById('mortgageResults');
// Reset UI
errorDiv.style.display = 'none';
resultsDiv.style.display = 'none';
// Validate Inputs
if (homePrice === "" || downPayment === "" || interestRate === "" || loanTerm === "") {
errorDiv.innerText = "Please fill in all fields.";
errorDiv.style.display = 'block';
return;
}
var P = parseFloat(homePrice); // Price
var D = parseFloat(downPayment); // Down Payment
var R = parseFloat(interestRate); // Annual Rate
var Y = parseFloat(loanTerm); // Years
if (isNaN(P) || isNaN(D) || isNaN(R) || isNaN(Y) || P <= 0 || Y = P) {
errorDiv.innerText = "Down payment cannot be equal to or greater than the home price.";
errorDiv.style.display = 'block';
return;
}
// Calculation Logic
var principal = P – D;
var monthlyRate = (R / 100) / 12;
var numberOfPayments = Y * 12;
var monthlyPayment = 0;
if (R === 0) {
monthlyPayment = principal / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPayment = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var totalPayment = monthlyPayment * numberOfPayments;
var totalInterest = totalPayment – principal;
// Update UI
document.getElementById('resMonthlyPayment').innerText = "$" + monthlyPayment.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resPrincipal').innerText = "$" + principal.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
document.getElementById('resTotalInterest').innerText = "$" + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
document.getElementById('resTotalCost').innerText = "$" + totalPayment.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
resultsDiv.style.display = 'block';
}
Understanding Your Mortgage Calculation
Purchasing a home is likely the largest financial commitment you will make in your lifetime. Understanding how your mortgage payments are calculated is crucial for financial planning. This Mortgage Payment Calculator helps you estimate your monthly obligations by factoring in the home price, down payment, interest rate, and loan term.
How is the Monthly Payment Calculated?
The calculation uses the standard amortization formula to determine the fixed monthly payment required to pay off your loan over the specified term. The key components include:
- Principal (P): This is the loan amount, calculated as the Home Price minus your Down Payment.
- Interest Rate (r): The annual percentage rate charged by the lender, divided by 12 to get the monthly rate.
- Number of Payments (n): The total number of months you will be paying the loan (e.g., 30 years = 360 months).
Typically, in the early years of a mortgage, a larger portion of your payment goes toward interest, while in later years, more is applied to the principal balance.
The Impact of Interest Rates and Down Payments
Even a small difference in the interest rate can significantly affect your total cost. For example, on a $300,000 loan, a 1% difference in interest rate can save or cost you tens of thousands of dollars over the life of a 30-year loan.
Similarly, a larger down payment reduces your principal amount, which not only lowers your monthly payment but also reduces the total interest paid. If you put down less than 20%, remember that lenders may require Private Mortgage Insurance (PMI), which is an additional cost not included in this basic principal and interest calculation.
Common Mortgage Terms Explained
Fixed-Rate Mortgage: The interest rate remains the same for the entire term of the loan, providing predictable monthly payments.
Adjustable-Rate Mortgage (ARM): The interest rate may change periodically based on market indices, potentially increasing or decreasing your monthly payment.
Use this calculator to experiment with different scenarios. Try adjusting the down payment or loan term to see how it fits your monthly budget and long-term financial goals.