Calculate your estimated monthly mortgage payment, total interest paid, and total amount paid over the life of the loan.
Your Estimated Mortgage Details
$0.00
Estimated Monthly Payment (Principal & Interest)
$0.00
Total Paid Over Loan Term
$0.00
Total Interest Paid
Understanding Your Mortgage Calculation
A mortgage is a loan used to purchase real estate. The monthly payment typically covers principal and interest. This calculator helps estimate these costs based on key loan parameters.
The Math Behind the Mortgage Payment
The standard formula for calculating a fixed-rate mortgage payment (M) is:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
P = Principal loan amount (the amount borrowed)
i = Monthly interest rate (annual rate divided by 12)
n = Total number of payments (loan term in years multiplied by 12)
How to Use This Calculator:
Loan Amount: Enter the total amount you plan to borrow for the property. This is your principal.
Annual Interest Rate: Input the yearly interest rate offered by the lender. The calculator will convert this to a monthly rate.
Loan Term (Years): Specify the duration of the loan, typically 15, 20, or 30 years. The calculator converts this into the total number of monthly payments.
Click "Calculate" to see your estimated monthly principal and interest (P&I) payment, the total amount you'll repay over the loan's life, and the total interest accrued.
Important Considerations:
This calculator provides an estimate for Principal and Interest (P&I) only. Your actual monthly mortgage payment may be higher and will likely include:
Property Taxes
Homeowner's Insurance
Private Mortgage Insurance (PMI) if your down payment is less than 20%
Homeowner Association (HOA) Dues
It's crucial to consult with a mortgage professional or lender for a precise quote based on your financial situation and current market conditions.
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTermYears = parseFloat(document.getElementById("loanTermYears").value);
var resultMonthlyPayment = document.getElementById("result-monthly-payment");
var resultTotalPayment = document.getElementById("result-total-payment");
var resultTotalInterest = document.getElementById("result-total-interest");
// Clear previous results and error messages
resultMonthlyPayment.textContent = "$0.00";
resultTotalPayment.textContent = "$0.00";
resultTotalInterest.textContent = "$0.00";
// Validate inputs
if (isNaN(loanAmount) || loanAmount <= 0 ||
isNaN(annualInterestRate) || annualInterestRate < 0 ||
isNaN(loanTermYears) || loanTermYears 0) {
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
} else {
// Handle the case of 0% interest rate
monthlyPayment = loanAmount / numberOfPayments;
}
// Calculate total payment and total interest
totalPayment = monthlyPayment * numberOfPayments;
totalInterest = totalPayment – loanAmount;
// Format results to currency
var formatter = new Intl.NumberFormat('en-US', {
style: 'currency',
currency: 'USD',
minimumFractionDigits: 2,
maximumFractionDigits: 2,
});
resultMonthlyPayment.textContent = formatter.format(monthlyPayment);
resultTotalPayment.textContent = formatter.format(totalPayment);
resultTotalInterest.textContent = formatter.format(totalInterest);
}