This calculator helps you estimate your monthly principal and interest payment for a mortgage.
It's a crucial tool for anyone considering purchasing a home, refinancing an existing loan,
or simply budgeting for homeownership costs. While this calculator focuses on the principal
and interest, remember that your actual monthly housing expense will likely include
property taxes, homeowner's insurance, and potentially Private Mortgage Insurance (PMI)
or Homeowner Association (HOA) fees. Bank of America offers a variety of mortgage products,
and consulting with a loan officer is the best way to get precise figures tailored to your situation.
How the Calculation Works
The monthly mortgage payment is calculated using the following standard formula for an annuity:
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. This is calculated by dividing your annual interest rate by 12. For example, if your annual rate is 6.5%, your monthly rate (i) is 0.065 / 12 = 0.00541667.
n = The total number of payments over the loan's lifetime. This is calculated by multiplying your loan term in years by 12. For a 30-year loan, n = 30 * 12 = 360.
Example Calculation
Let's say you are looking to borrow $300,000 with an annual interest rate of 6.5% over a 30-year term.
This calculation results in an estimated monthly principal and interest payment of approximately $1,896.20.
Important Considerations
When using this calculator, remember:
This is an estimate. Actual loan terms and rates may vary.
This calculation does not include escrow payments for taxes and insurance, which will increase your total monthly housing cost.
Consider consulting with a Bank of America mortgage specialist to explore loan options, understand all associated costs, and get a personalized pre-approval.
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var interestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseInt(document.getElementById("loanTerm").value);
var monthlyPaymentElement = document.getElementById("monthlyPayment");
if (isNaN(loanAmount) || isNaN(interestRate) || isNaN(loanTerm) || loanAmount <= 0 || interestRate < 0 || loanTerm <= 0) {
monthlyPaymentElement.textContent = "Please enter valid numbers.";
monthlyPaymentElement.style.color = "red";
return;
}
var monthlyInterestRate = interestRate / 100 / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
if (isNaN(monthlyPayment) || !isFinite(monthlyPayment)) {
monthlyPaymentElement.textContent = "Calculation error.";
monthlyPaymentElement.style.color = "red";
} else {
monthlyPaymentElement.textContent = "$" + monthlyPayment.toFixed(2);
monthlyPaymentElement.style.color = "#004a99"; // Reset color on success
}
}
// Optional: Trigger calculation on input change for a more dynamic feel
document.getElementById("loanAmount").addEventListener("input", calculateMortgage);
document.getElementById("interestRate").addEventListener("input", calculateMortgage);
document.getElementById("loanTerm").addEventListener("input", calculateMortgage);