#mortgage-calculator-container {
font-family: sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ccc;
border-radius: 8px;
background-color: #f9f9f9;
}
#mortgage-calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
}
.calculator-section {
margin-bottom: 15px;
}
.calculator-section label {
display: block;
margin-bottom: 5px;
font-weight: bold;
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}
.calculator-section input[type="number"],
.calculator-section input[type="text"] {
width: 100%;
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.calculator-section button {
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width: 100%;
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background-color: #45a049;
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#mortgage-result {
margin-top: 20px;
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font-size: 18px;
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background-color: #fff;
border-radius: 4px;
text-align: center;
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#mortgage-result span {
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.article-content h3 {
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Understanding Your Mortgage Payment
A mortgage is a significant financial commitment, and understanding how your monthly payment is calculated is crucial for budgeting and financial planning. This calculator helps you estimate your principal and interest payment based on the loan amount, the annual interest rate, and the loan term in years.
Loan Amount (Principal): This is the total amount of money you are borrowing from the lender to purchase your home. It's the sticker price of the house minus your down payment.
Annual Interest Rate: This is the percentage charged by the lender for borrowing the money. A lower interest rate means you'll pay less in interest over the life of the loan. Rates can fluctuate based on market conditions and your creditworthiness.
Loan Term (Years): This is the total number of years you have to repay the loan. Common mortgage terms are 15 or 30 years. A shorter term generally means higher monthly payments but less interest paid overall. A longer term results in lower monthly payments but more interest paid over time.
The formula used for this calculation is the standard annuity formula for loan amortization:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
- M = Your total monthly mortgage payment
- P = The principal loan amount
- i = Your monthly interest rate (annual rate divided by 12)
- n = The total number of payments over the loan's lifetime (loan term in years multiplied by 12)
Important Note: This calculator provides an estimate of your principal and interest payment only. Your actual total monthly housing expense will likely include other costs such as property taxes, homeowner's insurance, and potentially private mortgage insurance (PMI) or homeowners association (HOA) fees. These additional costs, often referred to as PITI (Principal, Interest, Taxes, and Insurance), should also be factored into your budget.
function calculateMortgage() {
var principal = parseFloat(document.getElementById("principal").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
if (isNaN(principal) || isNaN(annualInterestRate) || isNaN(loanTerm) || principal <= 0 || annualInterestRate < 0 || loanTerm <= 0) {
document.getElementById("mortgage-result").innerHTML = 'Please enter valid positive numbers for all fields.';
return;
}
var monthlyInterestRate = annualInterestRate / 100 / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPayment;
if (monthlyInterestRate === 0) {
monthlyPayment = principal / numberOfPayments;
} else {
monthlyPayment = principal * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
var formattedMonthlyPayment = monthlyPayment.toFixed(2);
document.getElementById("mortgage-result").innerHTML = 'Your estimated monthly mortgage payment is: