function calculateMortgage() {
// Get Input Values
var homePrice = parseFloat(document.getElementById('mc_home_price').value);
var downPayment = parseFloat(document.getElementById('mc_down_payment').value);
var interestRate = parseFloat(document.getElementById('mc_interest_rate').value);
var loanTermYears = parseFloat(document.getElementById('mc_loan_term').value);
var annualTax = parseFloat(document.getElementById('mc_property_tax').value);
var annualInsurance = parseFloat(document.getElementById('mc_insurance').value);
var monthlyHOA = parseFloat(document.getElementById('mc_hoa').value);
// Validate Inputs
if (isNaN(homePrice) || homePrice < 0) homePrice = 0;
if (isNaN(downPayment) || downPayment < 0) downPayment = 0;
if (isNaN(interestRate) || interestRate < 0) interestRate = 0;
if (isNaN(loanTermYears) || loanTermYears <= 0) loanTermYears = 30; // Default to 30 if invalid
if (isNaN(annualTax) || annualTax < 0) annualTax = 0;
if (isNaN(annualInsurance) || annualInsurance < 0) annualInsurance = 0;
if (isNaN(monthlyHOA) || monthlyHOA 0) {
var x = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPI = principal * ((monthlyRate * x) / (x – 1));
} else {
monthlyPI = principal / numberOfPayments;
}
// Monthly Tax and Insurance
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
// Total Monthly Payment
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance + monthlyHOA;
// Formatting currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Update UI
document.getElementById('mc_pi_result').textContent = formatter.format(monthlyPI);
document.getElementById('mc_tax_result').textContent = formatter.format(monthlyTax);
document.getElementById('mc_ins_result').textContent = formatter.format(monthlyInsurance);
document.getElementById('mc_hoa_result').textContent = formatter.format(monthlyHOA);
document.getElementById('mc_total_payment').textContent = formatter.format(totalMonthly);
// Show results
document.getElementById('mc_results_area').style.display = 'block';
}
How to Use This Mortgage Calculator
Buying a home is one of the largest financial decisions you will make. Our Mortgage Payment Calculator helps you estimate your monthly housing costs accurately by accounting for all major factors, including principal, interest, taxes, insurance, and HOA fees (often referred to as PITI).
Understanding the Input Factors
To get the most accurate estimate, it is important to understand what each field represents:
Home Price: The total purchase price of the property.
Down Payment: The upfront cash you pay toward the home purchase. A larger down payment reduces your loan principal and monthly interest costs.
Interest Rate: The annual percentage rate (APR) charged by the lender. Even a small difference in rate can significantly impact your monthly payment.
Loan Term: The duration of the loan. 30-year terms offer lower monthly payments, while 15-year terms save money on total interest.
Property Tax & Insurance: These are annual costs usually held in escrow and paid monthly. They vary by location and property value.
What is PITI?
Mortgage lenders look at your "PITI" to determine affordability. This stands for:
Principal: The money that goes toward paying down the loan balance.
Interest: The cost of borrowing the money.
Taxes: Property taxes paid to your local government.
Insurance: Homeowners insurance to protect against damage and liability.
How to Lower Your Monthly Mortgage Payment
If the estimated payment is higher than your budget allows, consider these strategies:
Increase your Down Payment: Putting 20% or more down eliminates Private Mortgage Insurance (PMI) and lowers the principal.
Shop for Lower Rates: Improve your credit score or compare different lenders to secure a lower interest rate.
Choose a Longer Term: Extending the loan from 15 to 30 years will lower monthly payments, though you will pay more interest over time.
Look in Lower Tax Areas: Property taxes can vary wildly between different counties and towns.
Note: This calculator provides estimates for planning purposes. Actual loan terms and closing costs may vary based on your lender and specific financial situation.