Loan Repayment Interest Calculator
body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
line-height: 1.6;
background-color: #f8f9fa;
color: #333;
margin: 0;
padding: 20px;
}
.loan-calc-container {
max-width: 800px;
margin: 30px auto;
background-color: #ffffff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 74, 153, 0.1);
display: flex;
flex-direction: column;
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h1 {
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margin-bottom: 30px;
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.input-section {
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.input-group input[type="number"],
.input-group input[type="text"] {
width: calc(100% – 20px);
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
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.input-group input[type="number"]:focus,
.input-group input[type="text"]:focus {
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box-shadow: 0 0 5px rgba(0, 74, 153, 0.3);
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color: white;
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border-radius: 5px;
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font-weight: 500;
cursor: pointer;
transition: background-color 0.3s ease;
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.calculate-btn:hover {
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width: 100%;
margin-top: 30px;
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border: 1px solid #004a99;
border-radius: 6px;
background-color: #e7f3ff;
text-align: center;
}
.result-section h2 {
color: #004a99;
margin-bottom: 15px;
font-weight: 600;
}
#loanInterestResult, #totalRepaymentResult, #totalInterestPaidResult {
font-size: 24px;
color: #28a745;
font-weight: bold;
display: block;
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/* Responsive Adjustments */
@media (max-width: 768px) {
.loan-calc-container {
padding: 20px;
}
.input-group input[type="number"],
.input-group input[type="text"] {
width: calc(100% – 16px);
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.result-section {
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#loanInterestResult, #totalRepaymentResult, #totalInterestPaidResult {
font-size: 20px;
}
.article-section h2 {
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}
.article-section h3 {
font-size: 20px;
}
}
Loan Repayment Interest Calculator
Your Loan Repayment Details
Estimated Monthly Payment:
$0.00
Total Amount to Repay:
$0.00
Total Interest Paid:
$0.00
Understanding Loan Repayment Interest
Borrowing money, whether for a car, a home, or personal expenses, usually involves interest. The loan repayment interest calculator helps you estimate the total cost of borrowing by breaking down your monthly payments and the total interest you'll pay over the life of the loan. Understanding these figures is crucial for making informed financial decisions and managing your budget effectively.
How the Calculator Works
The calculator uses standard financial formulas to estimate your loan repayment. It requires three key pieces of information:
- Loan Amount: The principal amount you are borrowing.
- Annual Interest Rate: The yearly percentage charged by the lender.
- Loan Term: The total duration of the loan, usually in years.
The calculator first determines the monthly interest rate and the total number of payments. Then, it applies the loan amortization formula to calculate your fixed monthly payment. From this, it derives the total repayment amount and the total interest paid.
The Formulas
The core of the calculation relies on the following formulas:
Monthly Interest Rate (r):
`r = Annual Interest Rate / 12 / 100`
Number of Payments (n):
`n = Loan Term (in years) * 12`
Monthly Payment (M):
`M = P * [r(1 + r)^n] / [(1 + r)^n – 1]`
Where P is the Principal Loan Amount.
Total Repayment:
`Total Repayment = Monthly Payment * Number of Payments`
Total Interest Paid:
`Total Interest Paid = Total Repayment – Loan Amount`
Why Use This Calculator?
- Budgeting: Accurately estimate how much your loan will cost each month, making it easier to fit into your budget.
- Comparison: Compare loan offers from different lenders. A lower advertised interest rate might not always mean a lower total cost if other terms differ.
- Financial Planning: Understand the long-term financial commitment of taking out a loan.
- Debt Management: Visualize the impact of interest on your borrowing and plan your repayment strategy.
By inputting your specific loan details, you gain a clear picture of the financial implications, empowering you to borrow responsibly.
function calculateLoanInterest() {
var loanAmount = parseFloat(document.getElementById("loanAmount").value);
var annualInterestRate = parseFloat(document.getElementById("annualInterestRate").value);
var loanTermYears = parseFloat(document.getElementById("loanTermYears").value);
var monthlyPaymentResult = document.getElementById("loanInterestResult");
var totalRepaymentResult = document.getElementById("totalRepaymentResult");
var totalInterestPaidResult = document.getElementById("totalInterestPaidResult");
// Clear previous results
monthlyPaymentResult.textContent = "$0.00";
totalRepaymentResult.textContent = "$0.00";
totalInterestPaidResult.textContent = "$0.00";
// Input validation
if (isNaN(loanAmount) || loanAmount <= 0) {
alert("Please enter a valid loan amount.");
return;
}
if (isNaN(annualInterestRate) || annualInterestRate < 0) {
alert("Please enter a valid annual interest rate.");
return;
}
if (isNaN(loanTermYears) || loanTermYears <= 0) {
alert("Please enter a valid loan term in years.");
return;
}
var monthlyInterestRate = annualInterestRate / 100 / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPayment;
if (monthlyInterestRate === 0) {
// Handle case of 0% interest rate
monthlyPayment = loanAmount / numberOfPayments;
} else {
// Standard amortization formula
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
var totalRepayment = monthlyPayment * numberOfPayments;
var totalInterestPaid = totalRepayment – loanAmount;
// Format results to two decimal places and add currency symbol
monthlyPaymentResult.textContent = "$" + monthlyPayment.toFixed(2);
totalRepaymentResult.textContent = "$" + totalRepayment.toFixed(2);
totalInterestPaidResult.textContent = "$" + totalInterestPaid.toFixed(2);
}