.calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
background: #fff;
padding: 20px;
border: 1px solid #eee;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
}
@media (max-width: 600px) {
.calc-grid {
grid-template-columns: 1fr;
}
}
.calc-input-group {
margin-bottom: 15px;
}
.calc-input-group label {
display: block;
margin-bottom: 5px;
font-weight: 600;
font-size: 14px;
color: #2c3e50;
}
.calc-input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ddd;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.calc-btn {
background-color: #0066cc;
color: white;
border: none;
padding: 15px 30px;
font-size: 18px;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background 0.3s;
font-weight: bold;
}
.calc-btn:hover {
background-color: #0052a3;
}
.calc-results {
background-color: #f8f9fa;
padding: 20px;
border-radius: 6px;
margin-top: 20px;
border-left: 5px solid #0066cc;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 15px;
}
.result-row.total {
border-top: 1px solid #ddd;
padding-top: 10px;
font-weight: bold;
font-size: 20px;
color: #0066cc;
}
.calc-article {
margin-top: 40px;
line-height: 1.6;
}
.calc-article h2 {
color: #2c3e50;
border-bottom: 2px solid #0066cc;
padding-bottom: 10px;
margin-top: 30px;
}
.calc-article h3 {
color: #444;
margin-top: 25px;
}
.calc-article p {
margin-bottom: 15px;
}
.calc-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.calc-article li {
margin-bottom: 8px;
}
.example-box {
background: #eef7ff;
padding: 15px;
border-radius: 4px;
border: 1px solid #cce5ff;
}
function calculateMortgagePayment() {
// Get inputs by ID
var price = parseFloat(document.getElementById('mc_home_price').value);
var down = parseFloat(document.getElementById('mc_down_payment').value);
var rate = parseFloat(document.getElementById('mc_interest_rate').value);
var years = parseFloat(document.getElementById('mc_loan_term').value);
var taxYearly = parseFloat(document.getElementById('mc_property_tax').value);
var insYearly = parseFloat(document.getElementById('mc_insurance').value);
// Validation
if (isNaN(price) || isNaN(down) || isNaN(rate) || isNaN(years)) {
alert("Please verify that all fields contain valid numbers.");
return;
}
// Defaults for optional fields
if (isNaN(taxYearly)) taxYearly = 0;
if (isNaN(insYearly)) insYearly = 0;
// Calculations
var principal = price – down;
var monthlyRate = (rate / 100) / 12;
var numberOfPayments = years * 12;
var monthlyPI = 0;
// Handle zero interest case or standard case
if (rate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var monthlyTax = taxYearly / 12;
var monthlyIns = insYearly / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns;
// Display Results
document.getElementById('res_pi').innerHTML = "$" + monthlyPI.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res_tax').innerHTML = "$" + monthlyTax.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res_ins').innerHTML = "$" + monthlyIns.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('res_total').innerHTML = "$" + totalMonthly.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('mc_result_area').style.display = 'block';
}
Mortgage Monthly Payment Calculator
Principal & Interest:
$0.00
Property Tax:
$0.00
Home Insurance:
$0.00
Total Monthly Payment:
$0.00
*Does not include HOA fees or PMI unless added to other costs.
Understanding Your Mortgage Payment
Calculating your monthly mortgage payment is the first critical step in the home buying process. This calculator helps prospective homeowners estimate their financial commitment by accounting for principal, interest, taxes, and insurance (often referred to as PITI).
How the Calculation Works
While the math can seem complex, the components are straightforward:
- Principal & Interest (P&I): This is the core of your loan repayment. The formula uses your loan amount (Home Price minus Down Payment), the interest rate, and the loan term to determine the amortization schedule.
- Property Taxes: Local governments assess taxes based on your property's value. This calculator divides the annual tax amount by 12 to find the monthly contribution.
- Homeowners Insurance: Lenders require insurance to protect the asset. Like taxes, this annual premium is broken down into monthly installments.
The Amortization Formula
The standard formula used by lenders to calculate the monthly principal and interest payment is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
Where:
M = Total monthly payment
P = Principal loan amount
i = Monthly interest rate (Annual Rate / 12)
n = Total number of payments (Years × 12)
Where:
M = Total monthly payment
P = Principal loan amount
i = Monthly interest rate (Annual Rate / 12)
n = Total number of payments (Years × 12)
Real-World Example
Let's look at a realistic scenario to understand how changing variables affects your wallet:
Imagine you are purchasing a home for $300,000.
- Scenario A (20% Down): You put down $60,000. Your loan amount is $240,000. At a 6.5% interest rate over 30 years, your Principal & Interest payment is approximately $1,517.
- Scenario B (5% Down): You put down only $15,000. Your loan amount rises to $285,000. At the same rate, your P&I jumps to approximately $1,801—a difference of nearly $300 per month just from the loan size difference.
Note: This example does not include Private Mortgage Insurance (PMI), which is typically required if your down payment is less than 20%.
Tips for Lowering Your Payment
If the calculated total is higher than your budget allows, consider these strategies:
- Increase your down payment: This reduces the principal and immediately lowers monthly costs.
- Improve your credit score: A better score often unlocks lower interest rates.
- Shop for insurance: Homeowners insurance premiums vary wildly between providers; shopping around can save $20-$50 per month.