Please check your inputs. Home price must be greater than down payment.
Estimated Monthly Payment$0.00
Principal & Interest:$0.00
Property Tax (Monthly):$0.00
Home Insurance (Monthly):$0.00
Total Interest Paid (Over Term):$0.00
Total Cost of Loan:$0.00
Payoff Date:—
Understanding Your Mortgage Calculation
Buying a home is one of the most significant financial decisions you will make. Using a reliable Mortgage Calculator helps you estimate your monthly payments and understand the long-term cost of your loan. This tool breaks down the Principal and Interest (P&I) alongside estimates for Property Taxes and Home Insurance, giving you a clearer picture of your "PITI" payment.
How the Monthly Payment is Calculated
Your monthly mortgage payment is primarily determined by four key factors:
Home Price: The total purchase price of the real estate property.
Down Payment: The upfront cash you pay towards the home. A larger down payment reduces the loan amount (principal), thereby lowering your monthly payments and total interest paid.
Interest Rate: The annual percentage rate charged by the lender. Even a small difference in rates can significantly impact the total cost of the loan over 15 or 30 years.
Loan Term: The duration of the loan. A 30-year term offers lower monthly payments but results in higher total interest costs compared to a 15-year term.
The Impact of Taxes and Insurance
Many first-time homebuyers focus solely on the mortgage rate, forgetting that their monthly check to the bank often includes escrows for:
Property Taxes: Assessed by your local government, usually based on the property's value. This calculator divides the annual amount by 12 to show the monthly burden.
Homeowners Insurance: Protects your property against damage. Lenders require this to protect their asset.
Amortization Explained
Mortgages use an amortization schedule. In the early years of your loan, a large portion of your payment goes toward interest. As time passes, the portion allocated to principal increases, building your home equity faster. Use this calculator to experiment with different down payments and terms to find a financing strategy that fits your budget.
function calculateMortgage() {
// Get Input Values
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var interestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = parseInt(document.getElementById('loanTerm').value);
var yearlyTax = parseFloat(document.getElementById('propertyTax').value);
var yearlyIns = parseFloat(document.getElementById('homeInsurance').value);
var errorDiv = document.getElementById('error-message');
var resultsDiv = document.getElementById('results-area');
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTermYears)) {
errorDiv.style.display = 'block';
errorDiv.innerHTML = "Please enter valid numbers in all fields.";
resultsDiv.style.display = 'none';
return;
}
if (downPayment >= homePrice) {
errorDiv.style.display = 'block';
errorDiv.innerHTML = "Down payment cannot equal or exceed the home price.";
resultsDiv.style.display = 'none';
return;
}
errorDiv.style.display = 'none';
// Calculation Logic
var principal = homePrice – downPayment;
var monthlyInterestRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
// Standard Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal *
(monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) /
(Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
var monthlyTax = yearlyTax / 12;
var monthlyIns = yearlyIns / 12;
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyIns;
var totalPaymentOverTerm = monthlyPI * numberOfPayments;
var totalInterest = totalPaymentOverTerm – principal;
// Calculate Payoff Date
var today = new Date();
var payoffYear = today.getFullYear() + loanTermYears;
var payoffMonth = today.toLocaleString('default', { month: 'long' });
var payoffDateString = payoffMonth + " " + payoffYear;
// Display Results
document.getElementById('totalMonthlyPayment').innerHTML = formatCurrency(totalMonthlyPayment);
document.getElementById('piPayment').innerHTML = formatCurrency(monthlyPI);
document.getElementById('taxPayment').innerHTML = formatCurrency(monthlyTax);
document.getElementById('insPayment').innerHTML = formatCurrency(monthlyIns);
document.getElementById('totalInterest').innerHTML = formatCurrency(totalInterest);
document.getElementById('totalCost').innerHTML = formatCurrency(totalPaymentOverTerm + (yearlyTax * loanTermYears) + (yearlyIns * loanTermYears));
document.getElementById('payoffDate').innerHTML = payoffDateString;
// Show Results
resultsDiv.style.display = 'block';
}
function formatCurrency(num) {
return new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' }).format(num);
}