*Calculations are estimates. Actual payments may vary by lender.
Understanding Your Mortgage Payment
Calculating your potential monthly housing costs is a critical first step in the home buying process. This Mortgage Payment Calculator is designed to give you a comprehensive view of what you will actually pay each month, going beyond just the loan repayment to include taxes, insurance, and HOA fees.
Components of a Mortgage Payment (PITI)
Mortgage lenders often refer to your payment as PITI. Here is what that acronym stands for and how each component affects your wallet:
Principal: The portion of your payment that reduces the loan balance. In the early years of a 30-year mortgage, this amount is small compared to interest.
Interest: The cost of borrowing money. This is determined by your interest rate and remaining loan balance. A lower rate can save you tens of thousands over the life of the loan.
Taxes: Property taxes are assessed by your local government. They are typically collected by your lender in an escrow account and paid annually on your behalf.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is usually divided into monthly installments and held in escrow.
How Interest Rates Impact Affordability
Even a small fluctuation in interest rates can drastically change your monthly payment. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate is approximately $200 per month. Use the calculator above to test different rate scenarios to see how they impact your budget.
The Impact of Loan Term
While a 30-year fixed mortgage is the most common choice because it offers lower monthly payments, a 15-year term allows you to build equity much faster and pay significantly less in total interest. However, the monthly commitment for a 15-year loan is roughly 40-50% higher than a 30-year loan for the same amount.
Don't Forget HOA Dues
If you are buying a condo or a home in a planned community, Homeowners Association (HOA) dues are a mandatory monthly cost. While these are usually paid directly to the association rather than the lender, they affect your debt-to-income ratio and overall affordability.
function calculateMortgage() {
// 1. Get Input Values
var homePrice = parseFloat(document.getElementById("homePrice").value);
var downPayment = parseFloat(document.getElementById("downPayment").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTermYears = parseFloat(document.getElementById("loanTerm").value);
var annualTax = parseFloat(document.getElementById("propertyTax").value);
var annualInsurance = parseFloat(document.getElementById("homeInsurance").value);
var monthlyHOA = parseFloat(document.getElementById("hoaDues").value);
// 2. Validate Inputs
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(loanTermYears)) {
alert("Please enter valid numbers for Price, Down Payment, Rate, and Term.");
return;
}
// Handle optional fields being empty
if (isNaN(annualTax)) annualTax = 0;
if (isNaN(annualInsurance)) annualInsurance = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
// 3. Calculation Logic
var loanAmount = homePrice – downPayment;
// Prevent negative loan amount
if (loanAmount <= 0) {
alert("Down payment cannot be greater than or equal to Home Price.");
return;
}
var monthlyInterestRate = (interestRate / 100) / 12;
var totalPayments = loanTermYears * 12;
var monthlyPrincipalInterest = 0;
// Special handling for 0% interest
if (interestRate === 0) {
monthlyPrincipalInterest = loanAmount / totalPayments;
} else {
// Standard Amortization Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var mathPower = Math.pow(1 + monthlyInterestRate, totalPayments);
monthlyPrincipalInterest = loanAmount * (monthlyInterestRate * mathPower) / (mathPower – 1);
}
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + monthlyHOA;
// 4. Update DOM with formatted results
document.getElementById("resPrincipal").innerHTML = "$" + monthlyPrincipalInterest.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById("resTax").innerHTML = "$" + monthlyTax.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById("resInsurance").innerHTML = "$" + monthlyInsurance.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById("resHOA").innerHTML = "$" + monthlyHOA.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById("resTotal").innerHTML = "$" + totalMonthlyPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
// Show results container
document.getElementById("resultsArea").style.display = "block";
}