.calc-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
color: #333;
line-height: 1.6;
}
.calculator-box {
background: #f9f9f9;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
margin-bottom: 40px;
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;
}
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
font-weight: 600;
margin-bottom: 5px;
font-size: 14px;
}
.input-group input {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-group input:focus {
border-color: #0073aa;
outline: none;
}
.calc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 15px 30px;
font-size: 16px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
transition: background-color 0.2s;
}
.calc-btn:hover {
background-color: #005177;
}
#calc-results {
margin-top: 30px;
padding-top: 20px;
border-top: 2px solid #e0e0e0;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
font-size: 16px;
}
.result-row.total {
font-weight: 800;
color: #0073aa;
font-size: 20px;
margin-top: 15px;
border-top: 1px dashed #ccc;
padding-top: 10px;
}
.calc-article h2 {
color: #2c3e50;
margin-top: 30px;
}
.calc-article p {
margin-bottom: 15px;
}
.calc-article ul {
margin-bottom: 20px;
padding-left: 20px;
}
.calc-article li {
margin-bottom: 8px;
}
.error-msg {
color: #d63638;
font-weight: bold;
display: none;
margin-top: 10px;
}
function calculateMortgage() {
// Get input values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var years = parseFloat(document.getElementById('loanTerm').value);
var annualRate = parseFloat(document.getElementById('interestRate').value);
var yearlyTax = parseFloat(document.getElementById('propertyTax').value);
var yearlyIns = parseFloat(document.getElementById('homeIns').value);
var errorDiv = document.getElementById('error-message');
var resultDiv = document.getElementById('calc-results');
// Reset error
errorDiv.style.display = 'none';
resultDiv.style.display = 'none';
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(years) || isNaN(annualRate) ||
isNaN(yearlyTax) || isNaN(yearlyIns) || homePrice <= 0 || years <= 0) {
errorDiv.style.display = 'block';
return;
}
// Loan Calculation Logic
var loanAmount = homePrice – downPayment;
if (loanAmount <= 0) {
errorDiv.innerText = "Down payment cannot be greater than or equal to home price.";
errorDiv.style.display = 'block';
return;
}
var monthlyRate = (annualRate / 100) / 12;
var numberOfPayments = years * 12;
var monthlyPrincipalInterest = 0;
// Handle 0% interest edge case
if (annualRate === 0) {
monthlyPrincipalInterest = loanAmount / numberOfPayments;
} else {
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPrincipalInterest = loanAmount *
(monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) /
(Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
var monthlyTax = yearlyTax / 12;
var monthlyIns = yearlyIns / 12;
var totalMonthly = monthlyPrincipalInterest + monthlyTax + monthlyIns;
var totalPaymentOverLife = (monthlyPrincipalInterest * numberOfPayments);
var totalInterest = totalPaymentOverLife – loanAmount;
var totalCostWithTaxIns = (totalMonthly * numberOfPayments);
// Display Results
document.getElementById('res-pi').innerText = "$" + monthlyPrincipalInterest.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('res-tax').innerText = "$" + monthlyTax.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('res-ins').innerText = "$" + monthlyIns.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('res-total').innerText = "$" + totalMonthly.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('res-loan-amount').innerText = "$" + loanAmount.toFixed(0).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
document.getElementById('res-total-interest').innerText = "$" + totalInterest.toFixed(0).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
document.getElementById('res-total-cost').innerText = "$" + totalCostWithTaxIns.toFixed(0).replace(/\B(?=(\d{3})+(?!\d))/g, ",");
resultDiv.style.display = 'block';
}
Mortgage Repayment Calculator
Please enter valid positive numbers for all fields.
Monthly Breakdown
Principal & Interest:
$0.00
Property Tax:
$0.00
Home Insurance:
$0.00
Total Monthly Payment:
$0.00
Loan Summary:
Loan Amount: $0
Total Interest Paid: $0
Total Cost of Loan: $0
Loan Amount: $0
Total Interest Paid: $0
Total Cost of Loan: $0
Understanding Your Mortgage Payments
Purchasing a home is one of the most significant financial decisions you will make. This Mortgage Repayment Calculator is designed to help you estimate your monthly housing costs accurately by factoring in principal, interest, taxes, and insurance (often referred to as PITI).
How the Mortgage Calculator Works
To get the most accurate estimate, it is important to understand the different components that make up your monthly payment:
- Principal: The portion of your payment that goes toward paying down the money you borrowed.
- Interest: The fee charged by the lender for borrowing the money. In the early years of a mortgage, a larger portion of your payment goes toward interest.
- Property Taxes: Taxes charged by your local government based on the value of your property. These are often bundled into your monthly mortgage payment through an escrow account.
- Home Insurance: Insurance that covers damages to your property. Lenders require this to protect the asset securing the loan.
Factors That Influence Your Monthly Payment
Several variables can significantly impact how much you pay each month:
- Down Payment: putting more money down upfront reduces your loan amount, which lowers your monthly principal and interest payments. Furthermore, if you put down less than 20%, you may be required to pay Private Mortgage Insurance (PMI), which increases costs.
- Loan Term: A 30-year term typically offers lower monthly payments than a 15-year term, but you will pay significantly more in interest over the life of the loan.
- Interest Rate: Even a fraction of a percentage point difference in your interest rate can save or cost you thousands of dollars over the lifespan of the mortgage. Your rate is influenced by your credit score and current market conditions.
Why Calculate "Total Cost"?
Many homebuyers focus solely on the monthly payment, but looking at the Total Interest Paid is crucial for long-term financial planning. By using this calculator, you can adjust the "Down Payment" or "Loan Term" fields to see how these changes affect the total cost of borrowing. For example, making a slightly larger down payment or securing a lower interest rate can drastically reduce the total interest paid over 30 years.
Frequently Asked Questions
Does this calculator include HOA fees?
Currently, this calculator focuses on PITI (Principal, Interest, Taxes, and Insurance). If you are buying a condo or a home in a community with Homeowners Association (HOA) fees, you should add that monthly amount on top of the "Total Monthly Payment" calculated above to get your full housing expense.
What is a good interest rate?
Interest rates fluctuate based on the economy and central bank policies. To ensure you are getting a competitive rate, shop around with multiple lenders and work on improving your credit score before applying.