Mortgage Payment Calculator
A mortgage payment calculator helps you estimate your monthly principal and interest payments on a home loan. This is a crucial tool when budgeting for a home purchase, as it allows you to understand a significant portion of your ongoing housing costs.
function calculateMortgage() {
var principal = parseFloat(document.getElementById("principal").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var resultDiv = document.getElementById("result");
if (isNaN(principal) || isNaN(interestRate) || isNaN(loanTerm) || principal <= 0 || interestRate < 0 || loanTerm <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPayment = (principal * monthlyInterestRate) / (1 – Math.pow(1 + monthlyInterestRate, -numberOfPayments));
if (isNaN(monthlyPayment) || !isFinite(monthlyPayment)) {
resultDiv.innerHTML = "Calculation error. Please check your inputs.";
return;
}
resultDiv.innerHTML = "
Estimated Monthly Payment:
$" + monthlyPayment.toFixed(2);
}
.calculator-container {
font-family: Arial, sans-serif;
border: 1px solid #ddd;
padding: 20px;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
}
.calculator-inputs {
display: grid;
grid-template-columns: 1fr;
gap: 15px;
}
.form-group {
display: flex;
flex-direction: column;
}
.form-group label {
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.form-group input[type="number"] {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.calculator-inputs button {
background-color: #4CAF50;
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
transition: background-color 0.3s ease;
}
.calculator-inputs button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 25px;
padding: 15px;
background-color: #e7f3fe;
border: 1px solid #b3e5fc;
border-radius: 4px;
text-align: center;
font-size: 18px;
color: #333;
}
.calculator-result h3 {
margin-top: 0;
color: #0277bd;
}