Calculate your estimated monthly mortgage payment for a 15-year fixed-rate loan.
Estimated Monthly Payment (Principal & Interest)
$0.00
Understanding the 15-Year Fixed Mortgage Payment Calculator
A 15-year fixed-rate mortgage is a popular home loan option that offers a consistent monthly payment for principal and interest over a 15-year term. This contrasts with adjustable-rate mortgages, where the interest rate and payment can fluctuate over time. The 15-year term means you'll pay off your mortgage faster than a traditional 30-year loan, leading to significant savings in total interest paid.
How the Calculator Works
The 15-Year Fixed Mortgage Payment Calculator uses a standard formula to determine your estimated monthly principal and interest (P&I) payment. The formula is derived from the annuity payment formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Your total monthly mortgage payment (principal and interest)
P = The principal loan amount (the amount you borrow)
i = Your monthly interest rate (annual rate divided by 12)
n = The total number of payments over the loan's lifetime (loan term in years multiplied by 12)
Key Components Explained
Loan Amount (P): This is the total sum of money you are borrowing to purchase your home. It's the principal amount on which interest is calculated.
Annual Interest Rate: This is the yearly rate charged by the lender, expressed as a percentage. The calculator converts this to a monthly rate (divided by 12) for the calculation.
Loan Term: For a 15-year fixed mortgage, this is fixed at 15 years. The calculator automatically sets the total number of payments (n) to 180 (15 years * 12 months/year).
Why Choose a 15-Year Fixed Mortgage?
Opting for a 15-year fixed mortgage typically comes with several advantages:
Faster Equity Build-up: You build equity in your home more quickly because a larger portion of your payment goes towards the principal balance each month.
Lower Total Interest Paid: By paying off the loan in half the time compared to a 30-year mortgage, you significantly reduce the total amount of interest paid over the life of the loan.
Interest Rate Stability: The "fixed" aspect guarantees your interest rate won't change, providing predictable monthly payments and making budgeting easier.
However, it's important to note that the monthly payments on a 15-year mortgage are generally higher than those for a 30-year mortgage with the same loan amount and interest rate, due to the shorter repayment period. This calculator helps you estimate these higher, but more beneficial, payments.
Using the Calculator
Simply enter the desired loan amount, your expected annual interest rate, and click "Calculate Payment". The calculator will provide an estimated monthly principal and interest payment. Remember, this estimate does not include property taxes, homeowner's insurance, or potential Private Mortgage Insurance (PMI), which are often included in your total monthly housing expense (escrow payment).
Example Calculation
Let's say you are purchasing a home and need a mortgage with the following details:
Total Number of Payments (n): 15 years * 12 months/year = 180
Apply the formula: M = 300000 [ 0.0056667(1 + 0.0056667)^180 ] / [ (1 + 0.0056667)^180 – 1]
Result: M ≈ $2,594.38
This means your estimated monthly principal and interest payment would be approximately $2,594.38.
function syncRates() {
var interestRateInput = document.getElementById('interestRate');
var interestRateSlider = document.getElementById('interestRateSlider');
interestRateInput.value = interestRateSlider.value;
// Optionally recalculate immediately or wait for button click
// calculateMortgage();
}
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById('loanAmount').value);
var annualInterestRate = parseFloat(document.getElementById('interestRate').value);
var loanTermYears = 15; // Fixed for a 15-year mortgage
var monthlyPaymentElement = document.getElementById('monthlyPayment');
monthlyPaymentElement.textContent = "$0.00"; // Reset to default
// Input validation
if (isNaN(loanAmount) || loanAmount <= 0) {
alert("Please enter a valid loan amount.");
return;
}
if (isNaN(annualInterestRate) || annualInterestRate <= 0) {
alert("Please enter a valid annual interest rate.");
return;
}
var monthlyInterestRate = annualInterestRate / 100 / 12;
var numberOfPayments = loanTermYears * 12;
// Mortgage Payment Formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
var numerator = monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments);
var denominator = Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1;
// Handle cases where denominator might be zero or extremely small due to floating point issues
if (denominator === 0) {
alert("Calculation error: Denominator is zero. Please check inputs.");
return;
}
var monthlyPayment = loanAmount * (numerator / denominator);
// Format the result to two decimal places
monthlyPaymentElement.textContent = "$" + monthlyPayment.toFixed(2);
}
// Initialize slider value with input value on page load if needed, or vice-versa.
// Here we sync slider to input value initially if they differ or if input is default.
var initialRate = parseFloat(document.getElementById('interestRate').value);
document.getElementById('interestRateSlider').value = initialRate;