.mc-container {
padding: 2rem;
}
.mc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.mc-grid {
grid-template-columns: 1fr;
}
}
.mc-input-group {
margin-bottom: 15px;
}
.mc-label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #333;
font-size: 0.95rem;
}
.mc-input {
width: 100%;
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 1rem;
box-sizing: border-box;
transition: border-color 0.3s;
}
.mc-input:focus {
border-color: #0073aa;
outline: none;
box-shadow: 0 0 0 2px rgba(0,115,170,0.2);
}
.mc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 15px 30px;
font-size: 1.1rem;
font-weight: bold;
border-radius: 6px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
}
.mc-btn:hover {
background-color: #005177;
}
.mc-results {
background-color: #f8f9fa;
border-top: 1px solid #e0e0e0;
padding: 2rem;
margin-top: 2rem;
display: none;
}
.mc-result-card {
text-align: center;
padding: 15px;
background: white;
border-radius: 6px;
border: 1px solid #eee;
margin-bottom: 15px;
}
.mc-result-label {
font-size: 0.9rem;
color: #666;
text-transform: uppercase;
letter-spacing: 0.5px;
}
.mc-result-value {
font-size: 2rem;
color: #2c3e50;
font-weight: bold;
margin: 10px 0;
}
.mc-breakdown {
display: flex;
justify-content: space-between;
font-size: 0.9rem;
padding: 5px 0;
border-bottom: 1px solid #eee;
}
.mc-article {
padding: 2rem;
background-color: #fff;
color: #444;
line-height: 1.6;
border-top: 5px solid #0073aa;
}
.mc-article h2 {
color: #2c3e50;
margin-top: 0;
}
.mc-article h3 {
color: #34495e;
margin-top: 1.5rem;
}
.mc-article p {
margin-bottom: 1rem;
}
.mc-article ul {
padding-left: 20px;
}
.mc-error {
color: #dc3232;
font-weight: bold;
display: none;
margin-top: 10px;
text-align: center;
}
function calculateMortgage() {
// Get Input Values
var homePrice = document.getElementById('homePrice').value;
var downPayment = document.getElementById('downPayment').value;
var interestRate = document.getElementById('interestRate').value;
var loanTerm = document.getElementById('loanTerm').value;
var errorDiv = document.getElementById('mcError');
var resultsDiv = document.getElementById('mcResults');
// Reset Error
errorDiv.style.display = 'none';
// Validate Inputs
if (homePrice === "" || downPayment === "" || interestRate === "" || loanTerm === "") {
errorDiv.innerText = "Please fill in all fields.";
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
// Parse numbers
var price = parseFloat(homePrice);
var down = parseFloat(downPayment);
var rate = parseFloat(interestRate);
var years = parseFloat(loanTerm);
// Validate Numbers
if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(years) || price < 0 || down < 0 || rate < 0 || years <= 0) {
errorDiv.innerText = "Please enter valid positive numbers.";
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
// Calculation Logic
var principal = price – down;
// Handle negative principal
if (principal <= 0) {
errorDiv.innerText = "Down payment cannot be greater than or equal to home price.";
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
var monthlyRate = (rate / 100) / 12;
var numPayments = years * 12;
var monthlyPayment = 0;
// Handle 0% interest edge case
if (rate === 0) {
monthlyPayment = principal / numPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var x = Math.pow(1 + monthlyRate, numPayments);
monthlyPayment = (principal * x * monthlyRate) / (x – 1);
}
var totalCost = monthlyPayment * numPayments;
var totalInterest = totalCost – principal;
// Display Results with Formatting
// Helper function for currency formatting
var formatCurrency = function(num) {
return "$" + num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
};
document.getElementById('resultMonthly').innerText = formatCurrency(monthlyPayment);
document.getElementById('resultPrincipal').innerText = formatCurrency(principal);
document.getElementById('resultInterest').innerText = formatCurrency(totalInterest);
document.getElementById('resultTotalCost').innerText = formatCurrency(totalCost);
// Show Results
resultsDiv.style.display = 'block';
// Scroll to results on mobile
if (window.innerWidth < 600) {
resultsDiv.scrollIntoView({ behavior: 'smooth' });
}
}
Mortgage Payment Calculator
Please enter valid positive numbers for all fields.
Estimated Monthly Payment
$0.00
(Principal & Interest Only)
Loan Breakdown
Loan Amount (Principal):
$0.00
Total Interest Cost:
$0.00
Total Cost of Loan:
$0.00
How to Calculate Your Mortgage Payment
Understanding your monthly financial obligation is the first step in the home-buying process. This Mortgage Payment Calculator helps you estimate your monthly Principal and Interest (P&I) payments based on the home's price, your down payment, the interest rate, and the loan term.
The Mortgage Formula
Mortgage amortization uses a specific compound interest formula to determine equal monthly payments over the life of the loan. The formula used is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
- M = Total monthly payment
- P = Principal loan amount (Home Price minus Down Payment)
- i = Monthly interest rate (Annual Rate divided by 12)
- n = Total number of payments (Loan Years multiplied by 12)
Real-World Example
Let's say you are purchasing a home for $350,000. You decide to put 20% down, which is $70,000, leaving you with a loan principal of $280,000.
If you secure a 30-year fixed-rate mortgage at an interest rate of 6.5%:
- Principal (P): $280,000
- Monthly Rate (i): 0.065 / 12 = 0.005416
- Number of Payments (n): 30 * 12 = 360
Using the calculator above, your estimated monthly payment for Principal and Interest would be approximately $1,769.79. Over the life of the loan, you would pay a total of $637,123, meaning the total interest cost is $357,123.
Important Considerations
Note that this calculation covers Principal and Interest only. Your actual monthly housing expense will likely be higher due to:
- Property Taxes: Usually 1-2% of the home's value annually.
- Homeowners Insurance: Protects against damage and liability.
- PMI (Private Mortgage Insurance): Required if your down payment is less than 20%.
- HOA Fees: Homeowners Association fees if applicable.
Use this tool to experiment with different down payment amounts and interest rates to see how they impact your monthly affordability.