Estimate your monthly payments, including taxes and insurance.
30 Years
20 Years
15 Years
10 Years
Principal & Interest:–
Property Tax (Monthly):–
Home Insurance (Monthly):–
HOA Fees (Monthly):–
Total Monthly Payment:–
Total Interest Paid (Over Loan Life):–
Total Loan Cost:–
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 = parseInt(document.getElementById('loanTerm').value);
var annualTax = parseFloat(document.getElementById('propertyTax').value);
var annualInsurance = parseFloat(document.getElementById('homeInsurance').value);
var monthlyHOA = parseFloat(document.getElementById('hoaFees').value);
// Default to 0 if inputs are empty
if (isNaN(homePrice)) homePrice = 0;
if (isNaN(downPayment)) downPayment = 0;
if (isNaN(interestRate)) interestRate = 0;
if (isNaN(annualTax)) annualTax = 0;
if (isNaN(annualInsurance)) annualInsurance = 0;
if (isNaN(monthlyHOA)) monthlyHOA = 0;
// 2. Calculate Loan Principal
var principal = homePrice – downPayment;
if (principal <= 0) {
alert("Down payment cannot be greater than or equal to the home price.");
return;
}
// 3. Calculate Monthly Principal & Interest
// Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyRate = (interestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPrincipalInterest = 0;
if (interestRate === 0) {
monthlyPrincipalInterest = principal / numberOfPayments;
} else {
var x = Math.pow(1 + monthlyRate, numberOfPayments);
monthlyPrincipalInterest = (principal * x * monthlyRate) / (x – 1);
}
// 4. Calculate Other Monthly Costs
var monthlyTax = annualTax / 12;
var monthlyInsurance = annualInsurance / 12;
// 5. Calculate Totals
var totalMonthlyPayment = monthlyPrincipalInterest + monthlyTax + monthlyInsurance + monthlyHOA;
var totalAmountPaidToBank = monthlyPrincipalInterest * numberOfPayments;
var totalInterestPaid = totalAmountPaidToBank – principal;
var totalLoanCost = totalAmountPaidToBank + (monthlyTax * numberOfPayments) + (monthlyInsurance * numberOfPayments) + (monthlyHOA * numberOfPayments);
// 6. Display Results
document.getElementById('resPrincipalInterest').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('resTotalMonthly').innerHTML = "$" + totalMonthlyPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('resTotalInterest').innerHTML = "$" + totalInterestPaid.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
document.getElementById('resTotalCost').innerHTML = "$" + totalLoanCost.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
// Show results div
document.getElementById('resultsArea').style.display = 'block';
}
Understanding Your Mortgage Calculation
Purchasing a home is likely the largest financial commitment you will make in your lifetime. Using a Mortgage Payment Calculator is an essential step in the home buying process. It helps you understand exactly how much house you can afford by breaking down the monthly costs associated with a home loan.
Components of a Mortgage Payment (PITI)
Most mortgage payments are made up of four key components, often referred to by the acronym PITI:
Principal: The portion of your payment that goes toward paying down the original amount you borrowed.
Interest: The cost of borrowing the money. In the early years of a fixed-rate mortgage, the majority of your payment goes toward interest.
Taxes: Property taxes assessed by your local government. Lenders typically collect a portion of this monthly and hold it in an escrow account to pay the bill when it's due.
Insurance: Homeowners insurance protects your property against damage. Like taxes, this is often escrowed into your monthly payment.
How Interest Rates Affect Your Payment
Even a small difference in interest rates can have a massive impact on your monthly payment and the total interest paid over the life of the loan. For example, on a $300,000 loan, the difference between a 6% and a 7% interest rate can change your monthly payment by nearly $200 and cost you tens of thousands of dollars more over 30 years.
Fixed-Rate vs. Adjustable-Rate Mortgages
This calculator assumes a Fixed-Rate Mortgage, where the interest rate remains the same for the entire loan term (usually 15 or 30 years). An Adjustable-Rate Mortgage (ARM) may start with a lower rate that changes after a set period (e.g., 5 or 7 years), which adds uncertainty to future payments.
The Impact of Your Down Payment
The down payment is the initial upfront payment you make. Putting at least 20% down typically allows you to avoid Private Mortgage Insurance (PMI), a monthly fee that protects the lender if you default. A larger down payment reduces the principal loan amount, thereby lowering your monthly interest costs.
Frequently Asked Questions
What is a good debt-to-income (DTI) ratio for a mortgage?
Lenders look at your DTI ratio to determine if you can afford monthly payments. Generally, lenders prefer a "front-end" DTI (housing costs divided by gross income) of no more than 28% and a "back-end" DTI (total debt payments divided by gross income) of no more than 36%.
Does the calculator include closing costs?
No, this calculator estimates your recurring monthly payments. Closing costs are one-time fees paid at the signing of the mortgage documents, typically ranging from 2% to 5% of the loan amount.
How can I lower my monthly mortgage payment?
You can lower your payment by increasing your down payment, securing a lower interest rate (by improving your credit score), extending the loan term (e.g., 30 years instead of 15), or finding a less expensive home to reduce the principal amount.