Estimate your potential monthly mortgage payments based on loan details.
Estimated Monthly Payment
$0.00
Understanding Your Home Loan Payments
Buying a home is a significant financial undertaking, and understanding your mortgage payments is crucial. A home loan, or mortgage, is a loan secured by a property. The loan amount is the principal sum borrowed from a lender, the interest rate is the cost of borrowing this money, and the loan term is the duration over which you repay the loan.
This calculator helps you estimate your Principal and Interest (P&I) monthly payment. It does not include other costs associated with homeownership, such as property taxes, homeowner's insurance, or potential Private Mortgage Insurance (PMI), which are often bundled into an actual mortgage payment (known as PITI – Principal, Interest, Taxes, and Insurance).
The Math Behind the Mortgage Payment
The most common formula used to calculate the monthly mortgage payment (M) is the standard annuity formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
P = Principal loan amount (the total amount you borrow).
i = Monthly interest rate. This is your Annual Interest Rate divided by 12. For example, if your annual rate is 6%, your monthly rate (i) is 0.06 / 12 = 0.005.
n = Total number of payments. This is your Loan Term in years multiplied by 12. For a 30-year loan, n = 30 * 12 = 360.
This formula calculates the fixed amount you will pay each month for the life of the loan, ensuring that by the end of the loan term, the entire principal is repaid along with all the accrued interest.
How to Use This Calculator:
Loan Amount: Enter the total amount you plan to borrow for your home.
Annual Interest Rate: Input the yearly interest rate offered by the lender. This is a critical factor affecting your monthly payment and total interest paid.
Loan Term (Years): Specify the duration of your loan in years (e.g., 15, 20, 30 years). Shorter terms generally mean higher monthly payments but less total interest paid over time.
Clicking "Calculate My Payment" will provide you with an estimated monthly principal and interest payment. It also shows the total amount you'll pay over the life of the loan and the total interest accumulated.
Important Considerations:
The results from this calculator are estimates. Actual mortgage offers may vary based on your creditworthiness, down payment, lender fees, and market conditions. Always consult with a mortgage professional for personalized advice and accurate quotes. Remember to factor in additional costs like property taxes, homeowner's insurance, and potential PMI when budgeting for your home.
function calculateMonthlyPayment() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var monthlyPaymentResult = document.getElementById("monthlyPayment");
var totalPaymentResult = document.getElementById("totalPayment");
var totalInterestResult = document.getElementById("totalInterest");
// Clear previous results if inputs are invalid
monthlyPaymentResult.textContent = "$0.00";
totalPaymentResult.textContent = "";
totalInterestResult.textContent = "";
// Validate inputs
if (isNaN(loanAmount) || loanAmount <= 0 ||
isNaN(interestRate) || interestRate <= 0 ||
isNaN(loanTerm) || loanTerm <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
var monthlyInterestRate = interestRate / 100 / 12;
var numberOfPayments = loanTerm * 12;
// Calculate monthly payment using the annuity formula
var monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
// Calculate total payment and total interest
var totalPayment = monthlyPayment * numberOfPayments;
var totalInterest = totalPayment – loanAmount;
// Format and display results
monthlyPaymentResult.textContent = "$" + monthlyPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
totalPaymentResult.textContent = "Total Paid Over Life of Loan: $" + totalPayment.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
totalInterestResult.textContent = "Total Interest Paid: $" + totalInterest.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}