Includes Principal, Interest, Taxes, Insurance & HOA
Payment Breakdown
Principal & Interest:$0.00
Property Tax:$0.00
Home Insurance:$0.00
HOA Fees:$0.00
Total Loan Amount:$0.00
Total Interest Paid (Over Life):$0.00
Total Cost of Mortgage:$0.00
function calculateMortgage() {
// Get Input Values using var
var homePrice = parseFloat(document.getElementById('homePrice').value);
var downPayment = parseFloat(document.getElementById('downPayment').value);
var loanTermYears = parseFloat(document.getElementById('loanTerm').value);
var interestRateAnnual = parseFloat(document.getElementById('interestRate').value);
var propertyTaxAnnual = parseFloat(document.getElementById('propertyTax').value);
var homeInsuranceAnnual = parseFloat(document.getElementById('homeInsurance').value);
var hoaFeesMonthly = parseFloat(document.getElementById('hoaFees').value);
// Validation
if (isNaN(homePrice) || isNaN(downPayment) || isNaN(loanTermYears) || isNaN(interestRateAnnual)) {
document.getElementById('errorMsg').style.display = 'block';
document.getElementById('calc-results').style.display = 'none';
return;
}
document.getElementById('errorMsg').style.display = 'none';
// Core Calculation Logic
var principal = homePrice – downPayment;
var monthlyInterestRate = (interestRateAnnual / 100) / 12;
var numberOfPayments = loanTermYears * 12;
// Principal & Interest Calculation (M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1 ])
var monthlyPI = 0;
if (interestRateAnnual === 0) {
monthlyPI = principal / numberOfPayments;
} else {
monthlyPI = principal * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
// Monthly Component Calculations
var monthlyTax = propertyTaxAnnual / 12;
var monthlyInsurance = homeInsuranceAnnual / 12;
// Total Monthly Payment
var totalMonthly = monthlyPI + monthlyTax + monthlyInsurance + hoaFeesMonthly;
// Total Loan Cost Calculations
var totalPIPaid = monthlyPI * numberOfPayments;
var totalInterestPaid = totalPIPaid – principal;
var totalCostOfLoan = totalPIPaid + (monthlyTax * numberOfPayments) + (monthlyInsurance * numberOfPayments) + (hoaFeesMonthly * numberOfPayments);
// Formatting Helper Function
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2
});
// Output Results
document.getElementById('totalMonthlyPayment').innerHTML = formatter.format(totalMonthly);
document.getElementById('piBreakdown').innerHTML = formatter.format(monthlyPI);
document.getElementById('taxBreakdown').innerHTML = formatter.format(monthlyTax);
document.getElementById('insBreakdown').innerHTML = formatter.format(monthlyInsurance);
document.getElementById('hoaBreakdown').innerHTML = formatter.format(hoaFeesMonthly);
document.getElementById('loanAmountResult').innerHTML = formatter.format(principal);
document.getElementById('totalInterestResult').innerHTML = formatter.format(totalInterestPaid);
document.getElementById('totalCostResult').innerHTML = formatter.format(totalCostOfLoan);
// Show Results Container
document.getElementById('calc-results').style.display = 'block';
}
Understanding Your Mortgage Payment
Calculating your monthly mortgage payment is one of the most critical steps in the home-buying process. While the sticker price of a home gives you a general idea of cost, your actual monthly obligation involves several components known collectively as PITI: Principal, Interest, Taxes, and Insurance.
1. Principal and Interest
The core of your mortgage payment consists of the principal (the amount you borrowed) and the interest (the cost of borrowing that money).
Principal: In the early years of a standard amortization schedule, a smaller portion of your payment goes toward reducing the principal balance.
Interest: Initially, the majority of your payment pays off the interest. As the principal decreases over time, the interest portion of your payment shrinks.
2. Property Taxes and Insurance
Most lenders require you to pay a portion of your estimated annual property taxes and homeowners insurance premiums each month. These funds are typically held in an escrow account and paid on your behalf when due.
Property Taxes: Assessed by your local government based on the value of your property. These can vary significantly by location.
Homeowners Insurance: Protects your property against damage. If you put down less than 20%, you may also be required to pay Private Mortgage Insurance (PMI), which protects the lender.
How Interest Rates Affect Buying Power
Even a small difference in interest rates can have a massive impact on your monthly payment and the total cost of the loan. For example, on a $300,000 loan, a 1% increase in interest rate can increase your monthly payment by hundreds of dollars and your total interest paid by tens of thousands over a 30-year term. Using this mortgage calculator allows you to stress-test your budget against rising rates.
Tips for Lowering Your Monthly Payment
Increase your Down Payment: Putting more money down reduces the principal loan amount and may eliminate the need for PMI.
Improve your Credit Score: Higher credit scores often qualify for lower interest rates.
Shop for Insurance: Homeowners insurance rates vary between providers; shopping around can save you money monthly.
Consider a Longer Term: While a 30-year term accrues more total interest than a 15-year term, the monthly payments are significantly lower.
What is an HOA Fee?
If you are buying a condo, townhouse, or a home in a planned community, you may be required to pay Homeowners Association (HOA) fees. These cover common area maintenance, amenities, and sometimes utilities. Unlike taxes and insurance, HOA fees are paid directly to the association, but lenders factor them into your Debt-to-Income (DTI) ratio when approving your loan.