Estimate your monthly house payments including taxes and insurance
30 Years
20 Years
15 Years
10 Years
Estimated Monthly Payment
$0.00
Includes Principal, Interest, Taxes, Insurance & HOA
Principal & Interest
$0.00
Loan Amount
$0.00
Total Interest
$0.00
function calculateMortgage() {
// 1. 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 loanTerm = parseInt(document.getElementById("mc-loan-term").value);
var annualTax = parseFloat(document.getElementById("mc-property-tax").value);
var annualInsurance = parseFloat(document.getElementById("mc-home-insurance").value);
var monthlyHOA = parseFloat(document.getElementById("mc-hoa-fees").value);
// 2. Validate inputs
if (isNaN(homePrice) || homePrice <= 0) {
alert("Please enter a valid Home Price.");
return;
}
if (isNaN(downPayment) || downPayment < 0) {
downPayment = 0;
}
if (isNaN(interestRate) || interestRate < 0) {
interestRate = 0;
}
if (isNaN(annualTax)) annualTax = 0;
if (isNaN(annualInsurance)) annualInsurance = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
// 3. Perform Calculations
var loanAmount = homePrice – downPayment;
// Prevent negative loan amounts
if (loanAmount 0 && interestRate > 0) {
monthlyPI = loanAmount * (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1);
} else if (loanAmount > 0 && interestRate === 0) {
monthlyPI = loanAmount / numberOfPayments;
}
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var totalMonthlyPayment = monthlyPI + monthlyTax + monthlyInsurance + monthlyHOA;
var totalCostOfLoan = (monthlyPI * numberOfPayments);
var totalInterest = totalCostOfLoan – loanAmount;
// 4. Update the DOM
// Helper for currency formatting
var fmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
document.getElementById("mc-total-monthly").innerHTML = fmt.format(totalMonthlyPayment);
document.getElementById("mc-pi-result").innerHTML = fmt.format(monthlyPI);
document.getElementById("mc-loan-amount").innerHTML = fmt.format(loanAmount);
// Handle case where interest might be negative or zero logic edge cases
if(totalInterest < 0) totalInterest = 0;
document.getElementById("mc-total-interest").innerHTML = fmt.format(totalInterest);
// Show results
document.getElementById("mc-results").style.display = "block";
}
Understanding Your Mortgage Calculation
Buying a home is one of the most significant financial decisions you will ever make. Using an accurate mortgage payment calculator is essential to understand exactly how much home you can afford. This tool breaks down your monthly financial obligation into its core components, often referred to as PITI: Principal, Interest, Taxes, and Insurance.
The Components of Your Monthly Payment
Principal: The portion of your payment that goes directly toward paying down the loan balance (the price of the home minus your down payment).
Interest: The fee charged by the lender for borrowing the money. In the early years of a 30-year mortgage, the majority of your payment goes toward interest rather than principal.
Property Taxes: Calculated by your local government based on the assessed value of your home. These are usually paid annually, but lenders often collect a monthly portion to hold in escrow.
Homeowners Insurance: Protects your property against damage. Like taxes, this is an annual cost often broken down into monthly escrow payments.
HOA Fees: If you live in a community with a Homeowners Association, these monthly dues are paid separately or included in your budget calculation, though usually not paid to the lender.
How Interest Rates Affect Affordability
Even a small change in interest rates can drastically alter your monthly payment and the total cost of the loan. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate can add hundreds of dollars to your monthly payment and tens of thousands of dollars in interest over the life of a 30-year term. It is crucial to shop around for the best rate and improve your credit score before applying.
Loan Term: 15-Year vs. 30-Year
The term of your loan determines your monthly payment and total interest paid:
30-Year Fixed: Offers lower monthly payments because the loan is spread over a longer period. However, you will pay significantly more in total interest.
15-Year Fixed: Requires higher monthly payments, but you build equity much faster and pay far less interest over the life of the loan.
Why Use This Calculator?
Unlike generic loan calculators, this specific mortgage tool accounts for "hidden" costs like property taxes and HOA fees. Lenders look at your Debt-to-Income (DTI) ratio based on the total monthly housing expense, not just the principal and interest. By inputting accurate estimates for taxes and insurance, you get a realistic view of your budget and can approach the home-buying process with confidence.