Please enter valid positive numbers for Home Price, Interest Rate, and Term.
Estimated Monthly Payment
$0.00
Principal & Interest$0.00
Property Tax$0.00
Home Insurance$0.00
HOA Fees$0.00
Loan Amount: $0
function calculateMortgage() {
// 1. Retrieve Input Elements
var priceInput = document.getElementById("homePrice");
var downInput = document.getElementById("downPayment");
var rateInput = document.getElementById("interestRate");
var termInput = document.getElementById("loanTerm");
var taxInput = document.getElementById("propertyTax");
var insInput = document.getElementById("homeInsurance");
var hoaInput = document.getElementById("hoaFees");
// 2. Parse Values
var price = parseFloat(priceInput.value);
var down = parseFloat(downInput.value) || 0;
var rate = parseFloat(rateInput.value);
var termYears = parseInt(termInput.value);
var yearlyTax = parseFloat(taxInput.value) || 0;
var yearlyIns = parseFloat(insInput.value) || 0;
var monthlyHoa = parseFloat(hoaInput.value) || 0;
// 3. Validation
var errorDiv = document.getElementById("errorMsg");
var resultsDiv = document.getElementById("results");
if (isNaN(price) || price <= 0 || isNaN(rate) || rate < 0 || isNaN(termYears)) {
errorDiv.style.display = "block";
resultsDiv.style.display = "none";
return;
}
errorDiv.style.display = "none";
// 4. Calculation Logic
var loanAmount = price – down;
if (loanAmount < 0) loanAmount = 0;
var monthlyRate = (rate / 100) / 12;
var numberOfPayments = termYears * 12;
var monthlyPI = 0;
// Standard Mortgage Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
if (rate === 0) {
monthlyPI = loanAmount / numberOfPayments;
} else {
monthlyPI = loanAmount * ( (monthlyRate * Math.pow(1 + monthlyRate, numberOfPayments)) / (Math.pow(1 + monthlyRate, numberOfPayments) – 1) );
}
var monthlyTax = yearlyTax / 12;
var monthlyIns = yearlyIns / 12;
var totalMonthly = monthlyPI + monthlyTax + monthlyIns + monthlyHoa;
// 5. Update UI
resultsDiv.style.display = "block";
// Helper for currency formatting
var fmt = new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD' });
document.getElementById("totalMonthly").innerHTML = fmt.format(totalMonthly);
document.getElementById("piBreakdown").innerHTML = fmt.format(monthlyPI);
document.getElementById("taxBreakdown").innerHTML = fmt.format(monthlyTax);
document.getElementById("insBreakdown").innerHTML = fmt.format(monthlyIns);
document.getElementById("hoaBreakdown").innerHTML = fmt.format(monthlyHoa);
document.getElementById("loanAmountDisplay").innerHTML = fmt.format(loanAmount);
}
Understanding Your Mortgage Payment Calculation
Buying a home is one of the largest financial decisions you will make in your lifetime. Understanding exactly where your monthly payment goes is crucial for financial planning. This calculator helps you break down the components of your mortgage payment, often referred to as PITI: Principal, Interest, Taxes, and Insurance.
How the Mortgage Formula Works
While the calculator above does the heavy lifting, it helps to understand the math behind the numbers. The standard formula used to calculate the Principal and Interest (P&I) portion of your loan is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ]
M = Total monthly payment
P = The principal loan amount (Home Price minus Down Payment)
i = Monthly interest rate (Annual rate divided by 12)
n = Total number of months (Loan years multiplied by 12)
Breakdown of Your Monthly Payment
Your "sticker price" monthly payment usually includes more than just paying back the bank. Here is what is included:
1. Principal
This is the money that goes directly towards paying down the balance of the loan. In the early years of a mortgage, this portion is small, but it grows over time as you pay off interest.
2. Interest
This is the cost of borrowing money. With a fixed-rate mortgage, the rate stays the same, but the dollar amount of interest you pay decreases every month as your principal balance shrinks.
3. Property Taxes
Local governments assess taxes on real estate to fund services like schools and roads. Lenders typically collect this monthly and hold it in an escrow account to pay the bill when it's due.
4. Homeowners Insurance
This policy protects your home against damage (fire, theft, storms). Like taxes, the premium is usually divided by 12 and paid monthly into your escrow account.
5. HOA Fees
If you buy a condo or a home in a planned community, you may have Homeowners Association (HOA) fees. While these are usually paid directly to the association, our calculator includes them to give you a true picture of your monthly housing cost.
How to Lower Your Monthly Mortgage Payment
If the estimated payment is higher than your budget allows, consider these strategies:
Increase your down payment: Paying more upfront reduces the loan principal and may eliminate Private Mortgage Insurance (PMI).
Shop for a lower interest rate: Even a 0.5% difference can save hundreds of dollars a month.
Extend the loan term: Moving from a 15-year to a 30-year term lowers monthly payments, though you will pay more interest in the long run.
Look for cheaper insurance: Shop around for homeowners insurance quotes to reduce that portion of your escrow.
{
"@context": "https://schema.org",
"@type": "FAQPage",
"mainEntity": [{
"@type": "Question",
"name": "What is included in a PITI mortgage payment?",
"acceptedAnswer": {
"@type": "Answer",
"text": "PITI stands for Principal, Interest, Taxes, and Insurance. These are the four standard components of a monthly mortgage payment."
}
}, {
"@type": "Question",
"name": "How does a larger down payment affect my monthly mortgage?",
"acceptedAnswer": {
"@type": "Answer",
"text": "A larger down payment lowers the principal loan amount, which directly reduces your monthly principal and interest payment. It may also remove the need for Private Mortgage Insurance (PMI)."
}
}]
}