Estimate your monthly house payments, including taxes, insurance, and HOA fees.
$
$
%
$
$
$
Please enter valid positive numbers for all fields.
Estimated Monthly Payment$0.00
Principal & Interest:$0.00
Property Tax (Monthly):$0.00
Home Insurance (Monthly):$0.00
HOA Fees (Monthly):$0.00
Total Loan Amount:$0.00
Total Interest Paid:$0.00
Understanding Your Mortgage Calculation
Buying a home is one of the largest financial decisions you will make. This mortgage calculator helps you understand exactly how much you can expect to pay each month by breaking down the "PITI" components: Principal, Interest, Taxes, and Insurance.
How the Formula Works
While the calculation involves complex amortization formulas, the primary variables affecting your monthly payment are:
Principal: The amount of money you borrow to purchase the home.
Interest: The cost of borrowing that money, expressed as an annual percentage rate.
Taxes: Property taxes assessed by your local government, usually bundled into your monthly escrow payment.
Insurance: Homeowners insurance to protect against damage, also typically paid via escrow.
Why Your Payment Might Be Higher Than Expected
Many first-time homebuyers only calculate the Principal and Interest (P&I). However, taxes, insurance, and Homeowners Association (HOA) fees can significantly increase your monthly obligation. This calculator includes input fields for these additional costs to provide a realistic monthly estimate.
Tips for Lowering Your Monthly Payment
Increase Your Down Payment: A larger down payment reduces the principal loan amount, thereby lowering the monthly payment and total interest paid.
Improve Your Credit Score: A higher credit score often qualifies you for a lower interest rate, which can save you tens of thousands of dollars over the life of the loan.
Shop for Insurance: Homeowners insurance rates vary. Comparing quotes from different providers can lower your monthly escrow costs.
Eliminate PMI: If your down payment is less than 20%, you may have to pay Private Mortgage Insurance. Saving for a 20% down payment removes this extra cost.
function calculateMortgage() {
// 1. Get Input Values by ID
var homePriceInput = document.getElementById('mc-home-price');
var downPaymentInput = document.getElementById('mc-down-payment');
var interestRateInput = document.getElementById('mc-interest-rate');
var loanTermInput = document.getElementById('mc-loan-term');
var propertyTaxInput = document.getElementById('mc-property-tax');
var homeInsuranceInput = document.getElementById('mc-home-insurance');
var hoaFeesInput = document.getElementById('mc-hoa-fees');
// 2. Parse Values to Floats
var homePrice = parseFloat(homePriceInput.value);
var downPayment = parseFloat(downPaymentInput.value);
var interestRate = parseFloat(interestRateInput.value);
var loanTerm = parseFloat(loanTermInput.value);
var propertyTaxYear = parseFloat(propertyTaxInput.value);
var homeInsuranceYear = parseFloat(homeInsuranceInput.value);
var hoaFeesMonth = parseFloat(hoaFeesInput.value);
// 3. Handle Empty Inputs (Set default zeros for optional fields if empty/NaN, strict for core fields)
if (isNaN(downPayment)) downPayment = 0;
if (isNaN(propertyTaxYear)) propertyTaxYear = 0;
if (isNaN(homeInsuranceYear)) homeInsuranceYear = 0;
if (isNaN(hoaFeesMonth)) hoaFeesMonth = 0;
var errorDiv = document.getElementById('mc-error');
var resultsDiv = document.getElementById('mc-results');
// 4. Validation
if (isNaN(homePrice) || isNaN(interestRate) || isNaN(loanTerm) || homePrice <= 0 || loanTerm = home price
if (loanAmount 0) {
monthlyPI = loanAmount / totalPayments;
}
} else {
// Standard Mortgage Formula: M = P[r(1+r)^n]/[(1+r)^n-1]
// P = loanAmount, r = monthlyInterestRate, n = totalPayments
var mathPower = Math.pow(1 + monthlyInterestRate, totalPayments);
monthlyPI = loanAmount * (monthlyInterestRate * mathPower) / (mathPower – 1);
}
// Monthly conversions for Tax and Insurance
var monthlyTax = propertyTaxYear / 12;
var monthlyInsurance = homeInsuranceYear / 12;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + hoaFeesMonth;
// Total Interest Calculation
var totalPaidOverLife = (monthlyPI * totalPayments);
var totalInterest = totalPaidOverLife – loanAmount;
if (totalInterest < 0) totalInterest = 0; // Edge case safety
// 6. Formatting Helper
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// 7. Update UI
document.getElementById('mc-result-monthly-total').innerHTML = formatter.format(totalMonthlyPayment);
document.getElementById('mc-result-pi').innerHTML = formatter.format(monthlyPI);
document.getElementById('mc-result-tax').innerHTML = formatter.format(monthlyTax);
document.getElementById('mc-result-ins').innerHTML = formatter.format(monthlyInsurance);
document.getElementById('mc-result-hoa').innerHTML = formatter.format(hoaFeesMonth);
document.getElementById('mc-result-loan-amount').innerHTML = formatter.format(loanAmount);
document.getElementById('mc-result-total-interest').innerHTML = formatter.format(totalInterest);
// Show results
resultsDiv.style.display = 'block';
}