Mortgage Payment Calculator
Your Estimated Monthly Mortgage Payment:
$0.00
.calculator-container {
font-family: Arial, sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
background-color: #f9f9f9;
}
.calculator-container h2 {
text-align: center;
margin-bottom: 20px;
color: #333;
}
.calculator-form {
margin-bottom: 20px;
}
.form-group {
margin-bottom: 15px;
display: flex;
align-items: center;
justify-content: space-between;
}
.form-group label {
margin-right: 10px;
font-weight: bold;
color: #555;
flex-basis: 50%;
}
.form-group input[type="number"] {
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
width: 50%;
box-sizing: border-box; /* Ensures padding doesn't affect width */
}
.calculator-form button {
background-color: #4CAF50;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 16px;
width: 100%;
margin-top: 10px;
}
.calculator-form button:hover {
background-color: #45a049;
}
.calculator-result {
text-align: center;
background-color: #e8f5e9;
padding: 15px;
border-radius: 4px;
border: 1px solid #c8e6c9;
}
.calculator-result h3 {
margin-top: 0;
color: #2e7d32;
}
#monthlyPayment {
font-size: 24px;
font-weight: bold;
color: #1b5e20;
}
function calculateMortgage() {
var principal = parseFloat(document.getElementById("principal").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTermYears = parseFloat(document.getElementById("loanTermYears").value);
if (isNaN(principal) || isNaN(annualInterestRate) || isNaN(loanTermYears) || principal <= 0 || annualInterestRate < 0 || loanTermYears <= 0) {
document.getElementById("monthlyPayment").innerText = "Invalid input. Please enter valid numbers.";
return;
}
var monthlyInterestRate = (annualInterestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPayment = (principal * monthlyInterestRate) / (1 – Math.pow(1 + monthlyInterestRate, -numberOfPayments));
if (isNaN(monthlyPayment) || !isFinite(monthlyPayment)) {
document.getElementById("monthlyPayment").innerText = "Calculation error.";
return;
}
document.getElementById("monthlyPayment").innerText = "$" + monthlyPayment.toFixed(2);
}
Understanding Your Mortgage Payment
A mortgage is a long-term loan used to purchase real estate. The monthly payment for a mortgage is typically composed of four main parts: Principal, Interest, Taxes, and Insurance (often referred to as PITI). This calculator focuses on estimating the principal and interest portion of your monthly payment, which is a significant component and is calculated using a standard mortgage formula.
The Mortgage Formula (Principal & Interest)
The formula used to calculate your monthly mortgage payment (P&I) is as follows:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
- M = Your total monthly mortgage payment (Principal & Interest)
- P = The principal loan amount (the amount you borrow)
- i = Your monthly interest rate (annual interest rate divided by 12)
- n = The total number of payments over the loan's lifetime (loan term in years multiplied by 12)
How to Use the Calculator
- Loan Principal: Enter the total amount you plan to borrow for your home.
- Annual Interest Rate: Input the yearly interest rate offered by your lender. For example, if the rate is 5%, enter '5'.
- Loan Term (Years): Specify the duration of your loan in years (e.g., 15, 20, or 30 years).
Clicking "Calculate Monthly Payment" will provide an estimate of the principal and interest you will pay each month. Remember that your actual total monthly payment may be higher due to property taxes, homeowner's insurance, and potentially Private Mortgage Insurance (PMI) or Homeowner Association (HOA) fees.
Example Calculation
Let's consider an example:
- You are borrowing $250,000 (Principal).
- The annual interest rate is 4.5%.
- The loan term is 30 years.
Using the calculator with these inputs:
- Monthly Interest Rate (i) = 4.5% / 12 = 0.045 / 12 = 0.00375
- Number of Payments (n) = 30 years * 12 months/year = 360
Plugging these into the formula or using the calculator would yield an estimated monthly principal and interest payment of approximately $1,265.33.