Your Estimated Monthly Repayment
Enter the details above to see your monthly repayment.
.calculator-wrapper {
font-family: sans-serif;
max-width: 700px;
margin: 20px auto;
padding: 20px;
border: 1px solid #ddd;
border-radius: 8px;
display: flex;
flex-wrap: wrap;
gap: 30px;
}
.calculator-inputs {
flex: 1;
min-width: 300px;
}
.calculator-results {
flex: 1;
min-width: 300px;
background-color: #f9f9f9;
padding: 20px;
border-radius: 8px;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
}
.input-group input {
width: calc(100% – 12px);
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
}
button {
background-color: #4CAF50;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 1em;
margin-top: 10px;
}
button:hover {
background-color: #45a049;
}
#result p {
font-size: 1.2em;
font-weight: bold;
color: #333;
text-align: center;
}
function calculateLoanRepayment() {
var loanAmountInput = document.getElementById("loanAmount");
var annualInterestRateInput = document.getElementById("annualInterestRate");
var loanTermYearsInput = document.getElementById("loanTermYears");
var resultDiv = document.getElementById("result");
var loanAmount = parseFloat(loanAmountInput.value);
var annualInterestRate = parseFloat(annualInterestRateInput.value);
var loanTermYears = parseFloat(loanTermYearsInput.value);
if (isNaN(loanAmount) || isNaN(annualInterestRate) || isNaN(loanTermYears) ||
loanAmount <= 0 || annualInterestRate < 0 || loanTermYears <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
var monthlyInterestRate = (annualInterestRate / 100) / 12;
var numberOfPayments = loanTermYears * 12;
var monthlyPayment = 0;
if (monthlyInterestRate === 0) {
monthlyPayment = loanAmount / numberOfPayments;
} else {
monthlyPayment = loanAmount * (monthlyInterestRate * Math.pow(1 + monthlyInterestRate, numberOfPayments)) / (Math.pow(1 + monthlyInterestRate, numberOfPayments) – 1);
}
if (isNaN(monthlyPayment) || !isFinite(monthlyPayment)) {
resultDiv.innerHTML = "Calculation error. Please check your inputs.";
return;
}
resultDiv.innerHTML = "$" + monthlyPayment.toFixed(2) + "";
}
Understanding Loan Repayments
When you take out a loan, whether it's for a car, a personal expense, or a business venture, understanding how your repayments are calculated is crucial. The monthly repayment amount is determined by three primary factors: the principal loan amount, the annual interest rate, and the loan term (the duration over which you'll repay the loan).
The formula used to calculate the monthly loan payment (M) is a standard amortization formula:
M = P [ i(1 + i)^n ] / [ (1 + i)^n – 1]
Where:
- M = Your total monthly loan payment
- P = The principal loan amount (the amount you borrow)
- i = Your monthly interest rate (annual rate divided by 12)
- n = The total number of payments over the loan's lifetime (loan term in years multiplied by 12)
This formula ensures that each payment contributes to both the principal repayment and the interest accrued over the loan's life. Early payments typically consist of a larger portion of interest, while later payments focus more on principal reduction.
Example:
Let's say you take out a personal loan of $15,000 with an annual interest rate of 6% and a loan term of 4 years.
- Principal (P) = $15,000
- Annual Interest Rate = 6%
- Monthly Interest Rate (i) = 6% / 12 = 0.06 / 12 = 0.005
- Loan Term = 4 years
- Number of Payments (n) = 4 years * 12 months/year = 48
Using the formula:
M = 15000 [ 0.005(1 + 0.005)^48 ] / [ (1 + 0.005)^48 – 1]
M = 15000 [ 0.005(1.005)^48 ] / [ (1.005)^48 – 1]
M = 15000 [ 0.005 * 1.270489 ] / [ 1.270489 – 1]
M = 15000 [ 0.006352445 ] / [ 0.270489 ]
M = 15000 * 0.0234851
M ≈ $352.28
Therefore, your estimated monthly repayment for this loan would be approximately $352.28. This calculator helps you quickly estimate these payments based on your specific loan details.