Amortization Schedule Calculator
Amortization Schedule
| Payment # |
Payment Date |
Payment Amount |
Principal Paid |
Interest Paid |
Remaining Balance |
.calculator-container {
font-family: sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}
.calculator-container h2 {
text-align: center;
margin-bottom: 20px;
color: #333;
}
.input-section {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
gap: 15px;
margin-bottom: 20px;
}
.form-group {
display: flex;
flex-direction: column;
}
.form-group label {
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.form-group input[type="number"],
.form-group select {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
}
.form-group input[type="number"]:focus,
.form-group select:focus {
border-color: #007bff;
outline: none;
}
button {
background-color: #007bff;
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
font-size: 1.1rem;
cursor: pointer;
transition: background-color 0.3s ease;
grid-column: 1 / -1; /* Span across all columns */
margin-top: 10px;
}
button:hover {
background-color: #0056b3;
}
.result-section {
margin-top: 20px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #dee2e6;
border-radius: 4px;
text-align: center;
font-size: 1.1rem;
color: #333;
}
.table-container {
margin-top: 30px;
overflow-x: auto;
}
.table-container h3 {
text-align: center;
margin-bottom: 15px;
color: #333;
}
#amortizationTable {
width: 100%;
border-collapse: collapse;
margin-top: 10px;
}
#amortizationTable th,
#amortizationTable td {
border: 1px solid #ddd;
padding: 10px;
text-align: right;
}
#amortizationTable th {
background-color: #f2f2f2;
font-weight: bold;
text-align: center;
}
#amortizationTable tbody tr:nth-child(even) {
background-color: #f9f9f9;
}
#amortizationTable td:first-child,
#amortizationTable td:nth-child(2) {
text-align: center;
}
function calculateAmortization() {
var principal = parseFloat(document.getElementById("principal").value);
var annualInterestRate = parseFloat(document.getElementById("interestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var paymentFrequency = parseInt(document.getElementById("paymentFrequency").value);
var resultDiv = document.getElementById("result");
var amortizationTableBody = document.querySelector("#amortizationTable tbody");
var amortizationTableContainer = document.getElementById("amortizationTableContainer");
// Clear previous results and table
resultDiv.innerHTML = "";
amortizationTableBody.innerHTML = "";
amortizationTableContainer.style.display = "none";
// Input validation
if (isNaN(principal) || principal <= 0) {
resultDiv.innerHTML = "Please enter a valid loan amount greater than zero.";
return;
}
if (isNaN(annualInterestRate) || annualInterestRate < 0) {
resultDiv.innerHTML = "Please enter a valid annual interest rate.";
return;
}
if (isNaN(loanTerm) || loanTerm <= 0) {
resultDiv.innerHTML = "Please enter a valid loan term greater than zero.";
return;
}
if (isNaN(paymentFrequency) || paymentFrequency 0) {
monthlyPayment = principal * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
} else {
monthlyPayment = principal / numberOfPayments; // Simple division if interest rate is 0
}
var totalInterestPaid = 0;
var remainingBalance = principal;
var currentDate = new Date();
for (var i = 0; i < numberOfPayments; i++) {
var interestPayment = remainingBalance * monthlyInterestRate;
var principalPayment = monthlyPayment – interestPayment;
// Adjust last payment to account for rounding and ensure balance is zero
if (i === numberOfPayments – 1) {
principalPayment = remainingBalance;
monthlyPayment = principalPayment + interestPayment;
}
remainingBalance -= principalPayment;
totalInterestPaid += interestPayment;
// Format date for display
var paymentDate = new Date(currentDate);
// A simple way to estimate dates, can be made more precise
paymentDate.setMonth(currentDate.getMonth() + i);
var formattedDate = paymentDate.toLocaleDateString('en-US', { year: 'numeric', month: 'short', day: 'numeric' });
var row = amortizationTableBody.insertRow();
row.insertCell(0).textContent = i + 1;
row.insertCell(1).textContent = formattedDate;
row.insertCell(2).textContent = monthlyPayment.toFixed(2);
row.insertCell(3).textContent = principalPayment.toFixed(2);
row.insertCell(4).textContent = interestPayment.toFixed(2);
row.insertCell(5).textContent = Math.max(0, remainingBalance).toFixed(2); // Ensure balance doesn't go negative
}
var totalPayment = monthlyPayment * numberOfPayments;
var totalPrincipalPaid = principal; // By the end of the loan, this should equal the principal
resultDiv.innerHTML =
"
Loan Summary
" +
"
Loan Amount: $" + principal.toFixed(2) + "" +
"
Annual Interest Rate: " + annualInterestRate.toFixed(2) + "%" +
"
Loan Term: " + loanTerm + " years (" + numberOfPayments + " payments)" +
"
Estimated Monthly Payment: $" + monthlyPayment.toFixed(2) + "" +
"
Total Principal Paid: $" + totalPrincipalPaid.toFixed(2) + "" +
"
Total Interest Paid: $" + totalInterestPaid.toFixed(2) + "" +
"
Total Amount Paid: $" + (totalPrincipalPaid + totalInterestPaid).toFixed(2) + "";
amortizationTableContainer.style.display = "block";
}
Understanding Loan Amortization
An amortization schedule is a table that details each periodic payment on an amortizing loan (like a mortgage or auto loan) over the full loan term. Each payment is broken down into two components: principal and interest.
Principal refers to the original amount of money borrowed. When you make a loan payment, a portion goes towards reducing this outstanding balance.
Interest is the cost of borrowing money, typically expressed as a percentage of the outstanding loan balance.
In the early stages of an amortizing loan, a larger portion of your payment goes towards interest, with a smaller amount reducing the principal. As time goes on and the outstanding balance decreases, the interest portion of your payment also decreases, and more of your payment goes towards paying down the principal. This is known as an amortization schedule.
The Amortization Schedule Calculator above helps you visualize this breakdown. By entering your loan amount, annual interest rate, loan term, and payment frequency, you can generate a detailed schedule showing how each payment contributes to reducing your debt and how much interest you'll pay over the life of the loan. This is a crucial tool for understanding your loan obligations and planning your finances effectively.
Key terms to understand:
- Loan Amount (Principal): The total amount of money you are borrowing.
- Annual Interest Rate: The yearly rate charged by the lender, expressed as a percentage.
- Loan Term: The duration over which the loan is to be repaid, usually in years.
- Payment Frequency: How often payments are made per year (e.g., monthly, quarterly, annually).
- Payment Amount: The fixed amount paid for each installment, which covers both principal and interest.
- Principal Paid: The portion of the payment that reduces the outstanding loan balance.
- Interest Paid: The portion of the payment that goes to the lender as the cost of borrowing.
- Remaining Balance: The outstanding debt after the current payment has been applied.
Using this calculator can help you compare different loan options, understand the long-term cost of borrowing, and make informed decisions about your financial commitments.