When you take out a mortgage with America First Credit Union, understanding how your monthly payment is calculated is crucial for financial planning. The primary components influencing your payment are the loan amount, the annual interest rate, and the loan term. This calculator helps you estimate these figures, providing a clear picture of your financial commitment.
The Math Behind Your Mortgage Payment
The standard formula for calculating a fixed-rate mortgage payment (P&I – Principal and Interest) is as follows:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Your total monthly mortgage payment (Principal & Interest)
P = The principal loan amount (the amount you borrowed)
i = Your monthly interest rate. This is calculated by dividing your annual interest rate by 12 (e.g., 5.5% annual rate / 12 months = 0.055 / 12 = 0.0045833).
n = The total number of payments over the loan's lifetime. This is calculated by multiplying the number of years in your loan term by 12 (e.g., a 30-year loan term has 30 * 12 = 360 payments).
How the Calculator Works:
This calculator takes the inputs you provide for Loan Amount (P), Annual Interest Rate, and Loan Term (in Years). It then converts these into the 'i' and 'n' values needed for the formula.
It calculates the monthly interest rate by dividing the annual rate by 100 (to convert percentage to decimal) and then by 12.
It calculates the total number of payments by multiplying the loan term in years by 12.
Finally, it plugs these values into the mortgage payment formula to determine your estimated monthly principal and interest payment.
The calculator also estimates:
Total Interest Paid: This is calculated by taking your total monthly payment, multiplying it by the total number of payments (n), and then subtracting the original principal loan amount (P). Total Interest = (M * n) – P.
Total Amount Paid: This is simply your estimated monthly payment (M) multiplied by the total number of payments (n). Total Paid = M * n.
Important Considerations for America First Mortgages:
Remember that this calculator provides an estimate for the principal and interest (P&I) portion of your monthly mortgage payment. Your actual total monthly housing expense with America First Credit Union will likely be higher and may include:
Property Taxes: Annual taxes divided by 12.
Homeowner's Insurance: Annual premium divided by 12.
Private Mortgage Insurance (PMI): If your down payment is less than 20%, PMI may be required.
Homeowner Association (HOA) Dues: If applicable to your property.
It's always recommended to speak directly with an America First mortgage loan officer for a personalized quote that includes all potential fees and costs associated with your specific loan scenario. This calculator is a valuable tool for initial budgeting and understanding the impact of different loan parameters.
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var monthlyPayment = 0;
var totalInterest = 0;
var totalPayment = 0;
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;
}
if (isNaN(loanTerm) || loanTerm 0) {
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
} else {
monthlyPayment = loanAmount / numberOfPayments; // Handle 0% interest case
}
totalPayment = monthlyPayment * numberOfPayments;
totalInterest = totalPayment – loanAmount;
document.getElementById("monthlyPayment").textContent = formatCurrency(monthlyPayment);
document.getElementById("totalInterest").textContent = formatCurrency(totalInterest);
document.getElementById("totalPayment").textContent = formatCurrency(totalPayment);
}
function formatCurrency(amount) {
return "$" + amount.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');
}
function resetCalculator() {
document.getElementById("loanAmount").value = "";
document.getElementById("annualInterestRate").value = "";
document.getElementById("loanTerm").value = "";
document.getElementById("monthlyPayment").textContent = "$0.00";
document.getElementById("totalInterest").textContent = "$0.00";
document.getElementById("totalPayment").textContent = "$0.00";
}