.mw-calc-wrapper {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 30px;
background: #ffffff;
border-radius: 12px;
box-shadow: 0 4px 20px rgba(0,0,0,0.08);
border: 1px solid #e0e0e0;
}
.mw-calc-title {
text-align: center;
color: #2c3e50;
margin-bottom: 25px;
font-size: 28px;
font-weight: 700;
}
.mw-input-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.mw-input-grid {
grid-template-columns: 1fr;
}
}
.mw-input-group {
margin-bottom: 15px;
}
.mw-input-group label {
display: block;
margin-bottom: 8px;
color: #555;
font-weight: 600;
font-size: 14px;
}
.mw-input-group input, .mw-input-group select {
width: 100%;
padding: 12px;
border: 1px solid #ddd;
border-radius: 6px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
.mw-input-group input:focus {
border-color: #3498db;
outline: none;
}
.mw-calc-btn {
grid-column: 1 / -1;
background-color: #2980b9;
color: white;
border: none;
padding: 15px;
font-size: 18px;
font-weight: bold;
border-radius: 8px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background 0.3s;
}
.mw-calc-btn:hover {
background-color: #2471a3;
}
.mw-results-container {
margin-top: 30px;
padding: 20px;
background-color: #f8f9fa;
border-radius: 8px;
border-left: 5px solid #27ae60;
display: none;
}
.mw-result-header {
font-size: 16px;
color: #7f8c8d;
text-transform: uppercase;
letter-spacing: 1px;
}
.mw-main-result {
font-size: 42px;
color: #27ae60;
font-weight: 800;
margin: 10px 0 20px 0;
}
.mw-breakdown-table {
width: 100%;
border-collapse: collapse;
margin-top: 15px;
}
.mw-breakdown-table td {
padding: 10px 0;
border-bottom: 1px solid #e0e0e0;
font-size: 15px;
}
.mw-breakdown-table tr:last-child td {
border-bottom: none;
}
.mw-breakdown-value {
text-align: right;
font-weight: 600;
color: #333;
}
.mw-article-content {
max-width: 800px;
margin: 40px auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
}
.mw-article-content h2 {
font-size: 26px;
color: #2c3e50;
margin-top: 30px;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
}
.mw-article-content h3 {
font-size: 22px;
color: #34495e;
margin-top: 25px;
}
.mw-article-content p {
margin-bottom: 15px;
font-size: 16px;
}
.mw-article-content ul {
margin-bottom: 20px;
padding-left: 20px;
}
.mw-article-content li {
margin-bottom: 8px;
}
.mw-error-msg {
color: #e74c3c;
text-align: center;
margin-top: 10px;
font-weight: bold;
display: none;
}
Mortgage Payment Calculator
Please enter valid numeric values.
$0.00
| Principal & Interest |
$0.00 |
| Property Tax |
$0.00 |
| Home Insurance |
$0.00 |
| HOA Fees |
$0.00 |
| Total Loan Amount |
$0.00 |
| Total Interest Paid |
$0.00 |
function calculateMortgage() {
// Get Inputs
var homePrice = parseFloat(document.getElementById('mw_home_price').value);
var downPayment = parseFloat(document.getElementById('mw_down_payment').value);
var interestRate = parseFloat(document.getElementById('mw_interest_rate').value);
var loanTermYears = parseFloat(document.getElementById('mw_loan_term').value);
var annualTax = parseFloat(document.getElementById('mw_property_tax').value);
var annualIns = parseFloat(document.getElementById('mw_insurance').value);
var monthlyHOA = parseFloat(document.getElementById('mw_hoa_fees').value);
var errorDiv = document.getElementById('mw_error');
var resultsDiv = document.getElementById('mw_results');
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTermYears)) {
errorDiv.style.display = 'block';
resultsDiv.style.display = 'none';
return;
}
// Handle edge case inputs to zero if empty
if (isNaN(annualTax)) annualTax = 0;
if (isNaN(annualIns)) annualIns = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
errorDiv.style.display = 'none';
// Calculation Logic
var principal = homePrice – downPayment;
// Prevent negative principal
if (principal < 0) principal = 0;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPrincipalInterest = 0;
// Calculate P&I
if (interestRate === 0) {
monthlyPrincipalInterest = principal / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var pow = Math.pow(1 + monthlyInterestRate, numberOfPayments);
monthlyPrincipalInterest = principal * ((monthlyInterestRate * pow) / (pow – 1));
}
var monthlyTax = annualTax / 12;
var monthlyIns = annualIns / 12;
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyIns + monthlyHOA;
var totalRepayment = (monthlyPrincipalInterest * numberOfPayments);
var totalInterestPaid = totalRepayment – principal;
// Display Results
document.getElementById('mw_total_monthly').innerHTML = formatMoney(totalMonthlyPayment);
document.getElementById('mw_res_pi').innerHTML = formatMoney(monthlyPrincipalInterest);
document.getElementById('mw_res_tax').innerHTML = formatMoney(monthlyTax);
document.getElementById('mw_res_ins').innerHTML = formatMoney(monthlyIns);
document.getElementById('mw_res_hoa').innerHTML = formatMoney(monthlyHOA);
document.getElementById('mw_res_loan_amt').innerHTML = formatMoney(principal);
document.getElementById('mw_res_total_interest').innerHTML = formatMoney(totalInterestPaid);
resultsDiv.style.display = 'block';
}
function formatMoney(amount) {
return '$' + amount.toLocaleString('en-US', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
}
How to Calculate Your Mortgage Payment
Buying a home is one of the most significant financial decisions you will make. Understanding how your monthly mortgage payment is calculated is crucial for budgeting and determining "how much house" you can afford. This Mortgage Calculator breaks down the components of your payment including Principal, Interest, Taxes, and Insurance (PITI).
Understanding the Components
Your monthly payment is typically composed of four main parts:
- Principal: This is the portion of your payment that goes directly toward paying down the loan balance (the amount you borrowed).
- Interest: This is the cost of borrowing money. In the early years of a mortgage, a large percentage of your payment goes toward interest.
- Taxes: Property taxes are assessed by your local government. Lenders often collect this monthly and put it into an escrow account to pay the bill when it's due.
- Insurance: Homeowners insurance protects against damage to the property. Like taxes, this is often paid via escrow.
How Interest Rates Affect Your Payment
Even a small change in interest rates can have a massive impact on your monthly payment and the total cost of the loan. For example, on a $300,000 loan, a difference of just 1% in the interest rate can change your monthly payment by over $150 and save (or cost) you nearly $60,000 in interest over the life of a 30-year loan.
The Mortgage Formula
While our calculator handles the math instantly, standard fixed-rate mortgages use the following amortization formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
- M = Total monthly payment
- P = Principal loan amount
- i = Monthly interest rate (Annual rate / 12)
- n = Number of months (Loan term in years × 12)
Why Use a Mortgage Calculator?
Using a calculator allows you to test different scenarios before speaking with a lender. By adjusting the "Down Payment" or "Home Price" fields, you can see exactly how much cash you need upfront to reach a target monthly payment that fits your budget.