Monthly Loan Calculator
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
line-height: 1.6;
color: #333;
background-color: #f8f9fa;
margin: 0;
padding: 20px;
}
.loan-calc-container {
max-width: 700px;
margin: 30px auto;
background-color: #fff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
display: flex;
flex-direction: column;
align-items: center;
}
h1 {
color: #004a99;
text-align: center;
margin-bottom: 25px;
font-weight: 600;
}
.input-section, .result-section {
width: 100%;
margin-bottom: 20px;
padding: 20px;
border: 1px solid #e0e0e0;
border-radius: 6px;
background-color: #fdfdfd;
}
.input-group {
margin-bottom: 18px;
display: flex;
flex-direction: column;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: 500;
color: #004a99;
}
.input-group input[type="number"],
.input-group input[type="text"],
.input-group select {
width: calc(100% – 20px); /* Account for padding */
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1rem;
box-sizing: border-box; /* Include padding and border in the element's total width and height */
}
.input-group input[type="number"]:focus,
.input-group input[type="text"]:focus,
.input-group select:focus {
border-color: #004a99;
outline: none;
box-shadow: 0 0 0 2px rgba(0, 74, 153, 0.2);
}
button {
background-color: #004a99;
color: white;
padding: 12px 25px;
border: none;
border-radius: 5px;
cursor: pointer;
font-size: 1.1rem;
transition: background-color 0.3s ease;
width: 100%;
max-width: 200px;
margin-top: 10px;
}
button:hover {
background-color: #003366;
}
.result-section {
background-color: #e6f2ff; /* Light blue background for result */
text-align: center;
border-left: 5px solid #004a99;
}
.result-section h2 {
color: #004a99;
margin-bottom: 15px;
font-weight: 600;
}
#monthlyPayment, #totalInterest, #totalPayment {
font-size: 1.8rem;
font-weight: bold;
color: #28a745; /* Success green for emphasis */
display: block;
margin-top: 10px;
}
.error-message {
color: #dc3545;
font-weight: bold;
margin-top: 10px;
}
.article-section {
width: 100%;
margin-top: 40px;
padding: 30px;
background-color: #fff;
border-radius: 8px;
box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}
.article-section h2 {
color: #004a99;
border-bottom: 2px solid #004a99;
padding-bottom: 10px;
margin-bottom: 20px;
font-weight: 600;
}
.article-section h3 {
color: #004a99;
margin-top: 20px;
margin-bottom: 10px;
}
.article-section p, .article-section ul {
margin-bottom: 15px;
}
.article-section code {
background-color: #e9ecef;
padding: 2px 5px;
border-radius: 3px;
font-family: Consolas, Monaco, 'Andale Mono', 'Ubuntu Mono', monospace;
}
@media (max-width: 600px) {
.loan-calc-container {
padding: 20px;
}
button {
width: 100%;
padding: 10px;
}
#monthlyPayment, #totalInterest, #totalPayment {
font-size: 1.5rem;
}
}
Monthly Loan Payment Calculator
Your Loan Details
—
Estimated Monthly Payment
—
Total Amount Paid
—
Total Interest Paid
Understanding Your Monthly Loan Payment
A monthly loan calculator is an essential tool for understanding the true cost of borrowing money. Whether you're considering a car loan, personal loan, or even a mortgage, knowing your estimated monthly payment, total repayment amount, and the total interest you'll pay over the life of the loan is crucial for financial planning.
The Math Behind the Calculation
The calculation for a fixed-rate loan's monthly payment uses a standard formula. The most common formula is the amortization formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
M = Your total monthly loan paymentP = The principal loan amount (the total amount you borrow)i = Your monthly interest rate (annual interest rate divided by 12)n = The total number of payments over the loan's lifetime (loan term in years multiplied by 12)
Our calculator takes your inputs for Loan Amount (P), Annual Interest Rate, and Loan Term (in years) and converts them into the values needed for this formula.
The Total Amount Paid is simply your monthly payment multiplied by the total number of payments (M * n).
The Total Interest Paid is the total amount paid back minus the original loan amount ((M * n) - P).
How to Use This Calculator
1. Loan Amount: Enter the total sum of money you wish to borrow.
2. Annual Interest Rate: Input the interest rate as a percentage (e.g., 5% is entered as 5).
3. Loan Term (Years): Specify the duration of the loan in years.
After entering these details, click "Calculate Payment" to see your estimated monthly payment, the total amount you'll repay, and the total interest accrued.
Why This Matters
Understanding your loan obligations helps you:
- Budget Effectively: Ensure the monthly payment fits comfortably within your budget.
- Compare Loans: Evaluate different loan offers by comparing their total costs.
- Avoid Surprises: Know the full financial commitment before signing loan agreements.
- Plan for the Future: Make informed decisions about taking on new debt.
This calculator provides an estimate based on a fixed-rate loan. Actual payments might vary slightly due to lender fees or specific loan structures.
function calculateMonthlyPayment() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTerm = parseFloat(document.getElementById("loanTerm").value);
var errorMessageElement = document.getElementById("errorMessage");
errorMessageElement.textContent = ""; // Clear previous errors
// — Input Validation —
if (isNaN(loanAmount) || loanAmount <= 0) {
errorMessageElement.textContent = "Please enter a valid positive loan amount.";
return;
}
if (isNaN(annualInterestRate) || annualInterestRate < 0) {
errorMessageElement.textContent = "Please enter a valid non-negative annual interest rate.";
return;
}
if (isNaN(loanTerm) || loanTerm <= 0) {
errorMessageElement.textContent = "Please enter a valid positive loan term in years.";
return;
}
// — Calculation Logic —
var monthlyInterestRate = annualInterestRate / 100 / 12;
var numberOfPayments = loanTerm * 12;
var monthlyPayment = 0;
var totalInterest = 0;
var totalPayment = 0;
// Handle the edge case where interest rate is 0
if (monthlyInterestRate === 0) {
monthlyPayment = loanAmount / numberOfPayments;
} else {
// Amortization formula: M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
totalPayment = monthlyPayment * numberOfPayments;
totalInterest = totalPayment – loanAmount;
// — Display Results —
document.getElementById("monthlyPayment").textContent = "$" + monthlyPayment.toFixed(2);
document.getElementById("totalPayment").textContent = "$" + totalPayment.toFixed(2);
document.getElementById("totalInterest").textContent = "$" + totalInterest.toFixed(2);
}