*Estimates only. Does not include PMI or utilities.
function calculateMortgage() {
// Get Inputs
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 = parseInt(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);
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTermYears)) {
alert("Please enter valid numbers for all main fields.");
return;
}
if (downPayment >= homePrice) {
alert("Down payment cannot be greater than or equal to the home price.");
return;
}
// Logic
var principal = homePrice – downPayment;
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
// Principal & Interest Calculation Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal * ( (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1) );
}
// Monthly breakdowns
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
// Handle NaN for optional fields if user cleared them
if (isNaN(monthlyTax)) monthlyTax = 0;
if (isNaN(monthlyInsurance)) monthlyInsurance = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + monthlyHOA;
// Output Results
document.getElementById('mc_total_result').innerHTML = '$' + totalMonthlyPayment.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('mc_pi_result').innerHTML = '$' + monthlyPI.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('mc_tax_result').innerHTML = '$' + monthlyTax.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('mc_ins_result').innerHTML = '$' + monthlyInsurance.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('mc_hoa_result').innerHTML = '$' + monthlyHOA.toLocaleString('en-US', {minimumFractionDigits: 2, maximumFractionDigits: 2});
// Show result box
document.getElementById('mc_result_box').classList.add('active');
}
Understanding Your Monthly Mortgage Payment
Purchasing a home is one of the most significant financial decisions you will make in your lifetime. While the listing price of a home is the headline number, the monthly mortgage payment is what ultimately dictates affordability for most buyers. Our Mortgage Monthly Payment Calculator is designed to give you a comprehensive view of what you can expect to pay every month, going beyond just the loan repayment to include taxes, insurance, and HOA fees.
The 4 Pillars of a Mortgage Payment (PITI)
To accurately budget for a new home, you must understand the four components that typically make up your monthly bill, often referred to by the acronym PITI:
Principal: This is the portion of your payment that goes directly toward paying down the loan balance. In the early years of a 30-year mortgage, this amount is small, but it grows over time.
Interest: This is the cost of borrowing money from your lender. With a standard amortization schedule, the majority of your payment in the first several years goes toward interest.
Taxes: Property taxes are assessed by your local government to fund public services. These are usually calculated as a percentage of the assessed home value and are often held in escrow by your lender.
Insurance: Homeowners insurance protects your property against damage and liability. Lenders require this coverage to protect the asset securing the loan.
How Interest Rates Affect Your Buying Power
Even a small fluctuation in interest rates can drastically change your monthly payment and total purchasing power. For example, on a $300,000 loan, the difference between a 6.0% and a 7.0% interest rate can increase your monthly payment by nearly $200. Using this calculator allows you to stress-test your budget against different rate scenarios to ensure you remain comfortable financially regardless of market volatility.
What About HOA Fees?
If you are buying a condo, townhome, or a house in a planned community, you will likely have to pay Homeowners Association (HOA) fees. These fees cover common area maintenance, amenities, and sometimes exterior insurance. Unlike property taxes and insurance, HOA fees are rarely included in your mortgage bill from the lender; you pay them directly to the association. However, lenders do factor them into your Debt-to-Income (DTI) ratio when qualifying you for a loan. Always input the specific HOA fees for a property into the calculator to get a true picture of affordability.
Strategies to Lower Your Monthly Payment
If the estimated payment looks too high, consider these strategies:
Increase Your Down Payment: Putting more money down reduces the principal loan amount and can eliminate the need for Private Mortgage Insurance (PMI).
Shop for Lower Insurance Rates: Insurance premiums vary significantly by provider. Bundling home and auto policies can often yield savings.
Buy Points: You can pay an upfront fee ("points") to your lender at closing to secure a lower interest rate for the life of the loan.
Extend the Loan Term: While a 30-year term is standard, some lenders offer 40-year terms. This lowers the monthly payment but increases the total interest paid over the life of the loan.
Frequency of Payments
While this calculator shows a monthly breakdown, many homeowners opt for bi-weekly payments. By paying half of your monthly payment every two weeks, you end up making 26 half-payments (or 13 full payments) per year. This strategy can shave years off your mortgage term and save thousands in interest.