Estimate your monthly payments, including taxes and insurance.
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Total Monthly Payment
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Principal & Interest
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Taxes & Fees (Monthly)
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Loan Amount
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Total Interest Paid
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Total Cost of Loan
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How to Calculate Your Mortgage Payment
Understanding the components of your monthly mortgage payment is crucial for financial planning when buying a home. This calculator breaks down the costs associated with homeownership, ensuring you have a clear picture of your financial commitment.
The 4 Major Components of a Mortgage (PITI)
Most mortgage payments consist of four primary parts, commonly referred to as PITI:
Principal: The portion of your payment that reduces the loan balance.
Interest: The cost of borrowing money, paid to the lender.
Taxes: Property taxes charged by your local government, usually held in escrow.
Insurance: Homeowners insurance to protect against fire, theft, and liabilities.
How Interest Rates Impact Affordability
Even a small change in interest rates can significantly affect your monthly payment and the total interest paid over the life of the loan. For example, on a $300,000 loan, a 1% increase in interest rate can add hundreds of dollars to your monthly payment and tens of thousands to the total cost of the loan.
Additional Costs to Consider
Beyond PITI, you may have other monthly obligations such as:
HOA Fees: If you buy a condo or a home in a planned community, you may pay Homeowners Association fees.
PMI (Private Mortgage Insurance): If your down payment is less than 20%, lenders usually require PMI, which protects them if you default.
Frequently Asked Questions
What is a good down payment for a house?
While 20% is the standard recommendation to avoid Private Mortgage Insurance (PMI), many lenders accept down payments as low as 3% to 5% for conventional loans, and 3.5% for FHA loans. The right amount depends on your savings and monthly budget.
How does the loan term affect my payment?
A shorter loan term (e.g., 15 years) typically comes with a lower interest rate and significantly lower total interest costs, but higher monthly payments. A longer term (e.g., 30 years) offers lower monthly payments but results in paying more interest over time.
Are property taxes and insurance always included in the mortgage payment?
Often, yes. Lenders usually collect these funds monthly and hold them in an escrow account to pay the bills when they are due. However, if you make a large down payment, you may have the option to pay taxes and insurance directly yourself.
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 loanTerm = parseInt(document.getElementById('loanTerm').value);
var propertyTax = parseFloat(document.getElementById('propertyTax').value);
var homeInsurance = parseFloat(document.getElementById('homeInsurance').value);
var hoaFees = parseFloat(document.getElementById('hoaFees').value);
// 2. Validation
var errorMsg = document.getElementById('errorMsg');
var resultsSection = document.getElementById('resultsSection');
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(interestRate) || isNaN(propertyTax) || isNaN(homeInsurance)) {
errorMsg.style.display = 'block';
resultsSection.style.display = 'none';
return;
}
if (homePrice < 0 || downPayment < 0 || interestRate < 0 || propertyTax < 0 || homeInsurance < 0) {
errorMsg.style.display = 'block';
errorMsg.innerText = "Values cannot be negative.";
resultsSection.style.display = 'none';
return;
}
errorMsg.style.display = 'none';
// 3. Calculation Logic
// Loan Amount (Principal)
var principal = homePrice – downPayment;
if (principal <= 0) {
errorMsg.style.display = 'block';
errorMsg.innerText = "Down payment cannot be greater than or equal to home price.";
resultsSection.style.display = 'none';
return;
}
// Monthly Interest Rate
var monthlyRate = (interestRate / 100) / 12;
// Total Number of Payments
var totalPayments = loanTerm * 12;
// Monthly Principal & Interest Payment Formula
// M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
var monthlyPI = 0;
if (interestRate === 0) {
monthlyPI = principal / totalPayments;
} else {
monthlyPI = principal * ( (monthlyRate * Math.pow(1 + monthlyRate, totalPayments)) / (Math.pow(1 + monthlyRate, totalPayments) – 1) );
}
// Monthly Taxes and Insurance
var monthlyTax = propertyTax / 12;
var monthlyInsurance = homeInsurance / 12;
// Total Monthly Payment
// Handle NaN for optional HOA fees if field is empty (though default is 0)
if (isNaN(hoaFees)) hoaFees = 0;
var monthlyTaxAndFees = monthlyTax + monthlyInsurance + hoaFees;
var totalMonthlyPayment = monthlyPI + monthlyTaxAndFees;
// Total Loan Cost metrics
var totalCostOfLoan = (monthlyPI * totalPayments);
var totalInterest = totalCostOfLoan – principal;
var totalCostWithFees = totalCostOfLoan + (monthlyTaxAndFees * totalPayments); // Estimate over full term
// 4. Update UI
// Helper for currency formatting
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2,
maximumFractionDigits: 2
});
document.getElementById('totalMonthlyResult').innerText = formatter.format(totalMonthlyPayment);
document.getElementById('piResult').innerText = formatter.format(monthlyPI);
document.getElementById('taxInsResult').innerText = formatter.format(monthlyTaxAndFees);
document.getElementById('loanAmountResult').innerText = formatter.format(principal);
document.getElementById('totalInterestResult').innerText = formatter.format(totalInterest);
document.getElementById('totalCostResult').innerText = formatter.format(totalCostOfLoan);
resultsSection.style.display = 'block';
// Scroll to results on mobile
if(window.innerWidth < 600) {
resultsSection.scrollIntoView({behavior: "smooth"});
}
}