Estimate your monthly payments including taxes, insurance, and HOA fees.
Principal & Interest:$0.00
Property Tax (Monthly):$0.00
Homeowners Insurance:$0.00
HOA Fees:$0.00
Total Monthly Payment:$0.00
Total Loan Amount:
function calculateMortgage() {
// 1. Get Input Values
var homePrice = parseFloat(document.getElementById("mcHomePrice").value);
var downPayment = parseFloat(document.getElementById("mcDownPayment").value);
var interestRate = parseFloat(document.getElementById("mcInterestRate").value);
var loanTerm = parseFloat(document.getElementById("mcLoanTerm").value);
var propertyTaxYear = parseFloat(document.getElementById("mcPropertyTax").value);
var insuranceYear = parseFloat(document.getElementById("mcInsurance").value);
var hoaMonth = parseFloat(document.getElementById("mcHOA").value);
// 2. Validate Inputs
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTerm)) {
alert("Please enter valid numbers for Home Price, Down Payment, Interest Rate, and Loan Term.");
return;
}
// Default optional fields to 0 if empty
if (isNaN(propertyTaxYear)) propertyTaxYear = 0;
if (isNaN(insuranceYear)) insuranceYear = 0;
if (isNaN(hoaMonth)) hoaMonth = 0;
// 3. Perform Calculations
var loanAmount = homePrice – downPayment;
// Handle edge case where loan amount is 0 or negative
if (loanAmount <= 0) {
alert("Down payment cannot be greater than or equal to Home Price.");
return;
}
// Monthly Interest Rate
var monthlyRate = (interestRate / 100) / 12;
// Total Number of Payments
var numberOfPayments = loanTerm * 12;
// Principal and Interest Calculation (Amortization Formula)
var monthlyPrincipalInterest = 0;
if (interestRate === 0) {
monthlyPrincipalInterest = loanAmount / numberOfPayments;
} else {
// M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
monthlyPrincipalInterest = loanAmount *
(monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) /
(Math.pow(1 + monthlyRate, numberOfPayments) – 1);
}
// Monthly Taxes and Insurance
var monthlyTax = propertyTaxYear / 12;
var monthlyInsurance = insuranceYear / 12;
// Total Monthly Payment
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + hoaMonth;
// 4. Update DOM with Results
// Helper function to format currency
function formatMoney(num) {
return num.toLocaleString('en-US', { style: 'currency', currency: 'USD' });
}
document.getElementById("resPrincipalInterest").innerHTML = formatMoney(monthlyPrincipalInterest);
document.getElementById("resTax").innerHTML = formatMoney(monthlyTax);
document.getElementById("resInsurance").innerHTML = formatMoney(monthlyInsurance);
document.getElementById("resHOA").innerHTML = formatMoney(hoaMonth);
document.getElementById("resTotal").innerHTML = formatMoney(totalMonthlyPayment);
document.getElementById("resLoanAmount").innerHTML = formatMoney(loanAmount);
// Show Results container
document.getElementById("mcResults").style.display = "block";
}
Understanding Your Mortgage Calculation
Buying a home is often the largest financial decision a person makes in their lifetime. Understanding exactly how your monthly payments are calculated is crucial for maintaining financial health. This Mortgage Payment Calculator is designed to give you a comprehensive view of your housing costs, going beyond just the loan repayment to include the "hidden" costs like taxes, insurance, and HOA fees.
The Four Pillars of a Mortgage Payment (PITI)
Lenders often refer to your monthly mortgage obligation as PITI. It stands for Principal, Interest, Taxes, and Insurance. Here is what each component means for your wallet:
Principal: This is the portion of your payment that goes directly toward paying down the balance of the loan. In the early years of a 30-year mortgage, the principal portion is very small, but it grows over time as the interest portion decreases.
Interest: This is the cost of borrowing money. Calculated based on your Annual Percentage Rate (APR), this is the profit the bank makes. A higher interest rate significantly increases your monthly payment and the total cost of the home.
Taxes: Property taxes are assessed by your local government to fund schools, roads, and emergency services. These are usually paid annually, but lenders often divide the annual cost by 12 and collect it monthly, holding it in an escrow account until the bill is due.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is often paid into an escrow account monthly. If you put less than 20% down, you may also have to pay Private Mortgage Insurance (PMI), which protects the lender, not you.
How Interest Rates Impact Affordability
Even a small fluctuation in interest rates can drastically change your buying power. For example, on a $400,000 loan, the difference between a 6% and a 7% interest rate might seem small (1%), but it can result in hundreds of dollars of difference in your monthly payment and tens of thousands of dollars in extra interest paid over the life of the loan.
When using the calculator above, try adjusting the interest rate field to see how sensitive your monthly budget is to current market rates. This can help you decide whether to buy points to lower your rate or wait for market conditions to improve.
The Role of Down Payments
Your down payment reduces the Loan-to-Value (LTV) ratio. A larger down payment reduces the principal loan amount, which lowers your monthly interest costs. Furthermore, putting down 20% or more typically allows you to avoid Private Mortgage Insurance (PMI), saving you an additional 0.5% to 1% of the loan amount annually.
What About HOA Fees?
If you are buying a condo, townhome, or a house in a planned community, you will likely encounter Homeowners Association (HOA) fees. These cover common area maintenance, amenities, and sometimes exterior building maintenance. While HOA fees are not paid to the lender, lenders do factor them into your Debt-to-Income (DTI) ratio when qualifying you for a loan. Always include these in your calculation to ensure you aren't house poor.
Tips for Using This Calculator
To get the most accurate result, check your local county assessor's website for the property tax rate in your target area. Property taxes can vary wildly from town to town. Similarly, get a quote for homeowners insurance early in the process. By inputting accurate tax and insurance numbers, you ensure that the "Total Monthly Payment" figure reflects reality, preventing unpleasant surprises at the closing table.