A 15-year fixed-rate mortgage is a popular home loan option that offers a predictable repayment schedule and a lower total interest cost compared to longer-term loans, like the more common 30-year mortgage. In this type of mortgage, you agree to repay the loan over 15 years, and your interest rate remains the same for the entire duration of the loan, providing stability and making budgeting easier.
How the 15-Year Fixed Mortgage Calculator Works
This calculator helps you estimate your principal and interest (P&I) monthly payment for a 15-year fixed-rate mortgage. It uses a standard amortization formula to determine this figure. The formula considers three key inputs:
Loan Amount: The total amount of money you are borrowing to purchase your home.
Annual Interest Rate: The yearly rate charged by the lender, expressed as a percentage. This rate is fixed for the life of the loan.
Loan Term: Fixed at 15 years (180 months) for this calculator.
The Mortgage Payment Formula
The monthly payment (M) for a fixed-rate mortgage is calculated using the following 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 borrowed).
i = Your monthly interest rate. This is your annual interest rate divided by 12 (e.g., 4.5% annual rate / 12 = 0.00375 monthly rate).
n = The total number of payments over the loan's lifetime. For a 15-year mortgage, this is 15 years * 12 months/year = 180 payments.
Why Choose a 15-Year Fixed Mortgage?
Lower Total Interest Paid: By paying off your loan faster, you significantly reduce the total amount of interest you pay over the life of the loan.
Build Equity Faster: A larger portion of your early payments goes towards the principal, allowing you to build home equity more quickly.
Predictable Payments: The fixed interest rate ensures your principal and interest payment never changes, offering great budget predictability.
Shorter Debt Period: You'll be mortgage-free in half the time compared to a traditional 30-year loan.
Considerations
While beneficial, a 15-year mortgage typically comes with higher monthly payments than a 30-year mortgage because you're paying off the same amount in less time. Ensure your budget can comfortably accommodate these higher payments. This calculator focuses only on the principal and interest; remember to factor in other costs like property taxes, homeowner's insurance, and potentially private mortgage insurance (PMI) for your total housing expense.
function updateInterestRate() {
var sliderValue = document.getElementById("interestRateSlider").value;
var interestRate = parseFloat(sliderValue) / 100; // Convert slider value (e.g., 450) to percentage (4.50)
document.getElementById("interestRate").value = interestRate.toFixed(2);
}
function formatCurrency(amount) {
return "$" + amount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("interestRate").value);
var loanTermYears = 15;
var numberOfPayments = loanTermYears * 12;
var monthlyInterestRate = annualInterestRate / 100 / 12;
var monthlyPayment = 0;
if (isNaN(loanAmount) || isNaN(annualInterestRate) || loanAmount <= 0 || annualInterestRate {
var initialRate = parseFloat(document.getElementById("interestRate").value);
document.getElementById("interestRateSlider").value = initialRate * 100; // Slider expects value * 100
});