Calculate your estimated monthly mortgage payment.
Your Estimated Monthly Payment:$0.00
Understanding Your Mortgage Payment
A mortgage is a loan used to purchase real estate. The monthly payment for a mortgage typically consists of several components, with the principal and interest (P&I) being the most significant. Our calculator focuses on these core components to provide an estimated monthly payment.
How the Calculation Works (The P&I Formula)
The standard formula used to calculate the fixed monthly payment (M) for a mortgage is derived from the amortization formula:
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 total amount you borrow)
i = Your monthly interest rate. This is calculated by dividing your annual interest rate by 12. For example, a 4.5% annual rate becomes (4.5 / 100) / 12 = 0.00375.
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. For example, a 30-year mortgage has 30 * 12 = 360 payments.
Key Inputs Explained:
Loan Amount (Principal): This is the total sum of money you are borrowing from the lender to buy your property. It does not include down payment or closing costs.
Annual Interest Rate: This is the yearly rate charged by the lender for borrowing the money. It's crucial to understand that this is an annual figure, and the calculation uses the *monthly* interest rate.
Loan Term (Years): This is the total duration of the loan, typically expressed in years (e.g., 15, 20, 30 years). A longer loan term means lower monthly payments but more interest paid over time. A shorter term means higher monthly payments but less total interest.
Beyond Principal and Interest (P&I)
It's important to note that the calculated monthly payment in this tool is for Principal and Interest (P&I) only. Most mortgage payments also include:
Property Taxes: Funds collected by your lender on behalf of local government tax authorities.
Homeowner's Insurance: Coverage for damage to your home.
Private Mortgage Insurance (PMI): Often required if your down payment is less than 20% of the home's purchase price.
Homeowner Association (HOA) Fees: If applicable to your property.
These additional costs, often referred to as "PITI" (Principal, Interest, Taxes, and Insurance), will increase your actual total monthly housing expense. Lenders usually collect these amounts along with your P&I payment and hold them in an escrow account to pay the bills when they are due.
Why Use a Mortgage Calculator?
A mortgage calculator is an essential tool for anyone considering buying a home. It helps you:
Budget Effectively: Understand how much house you can realistically afford based on your income and desired monthly payment.
Compare Loan Options: See how different interest rates and loan terms affect your monthly payment and the total interest paid over the life of the loan.
Negotiate Better: Be an informed borrower when speaking with lenders and comparing offers.
Plan for the Future: Estimate the impact of potential rate changes or consider making extra payments to pay down the loan faster.
Use this calculator as a starting point for your homeownership journey!
function calculateMortgage() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseInt(document.getElementById("loanTerm").value);
var monthlyPaymentElement = document.getElementById("monthlyPayment");
monthlyPaymentElement.textContent = "$0.00"; // Reset previous result
if (isNaN(loanAmount) || isNaN(annualInterestRate) || isNaN(loanTerm) || loanAmount <= 0 || annualInterestRate < 0 || loanTerm <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
var monthlyInterestRate = (annualInterestRate / 100) / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPayment;
if (monthlyInterestRate === 0) { // Handle case of 0% interest rate
monthlyPayment = loanAmount / numberOfPayments;
} else {
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
monthlyPaymentElement.textContent = "$" + monthlyPayment.toFixed(2);
}
// Optional: Add event listeners to update slider values when they change
document.getElementById("loanAmount").addEventListener("input", function() {
document.getElementById("loanAmount").value = this.value;
});
document.getElementById("interestRate").addEventListener("input", function() {
document.getElementById("interestRate").value = this.value;
});
document.getElementById("loanTerm").addEventListener("input", function() {
document.getElementById("loanTerm").value = this.value;
});