function calculateFD() {
// 1. Get Input Values
var amount = parseFloat(document.getElementById('depositAmount').value);
var rate = parseFloat(document.getElementById('interestRate').value);
var months = parseFloat(document.getElementById('tenureMonths').value);
var wht = parseFloat(document.getElementById('whtRate').value);
var payoutType = document.getElementById('interestPayout').value;
// 2. Input Validation
if (isNaN(amount) || amount <= 0) {
alert("Please enter a valid Deposit Amount.");
return;
}
if (isNaN(rate) || rate < 0) {
alert("Please enter a valid Interest Rate.");
return;
}
if (isNaN(months) || months <= 0) {
alert("Please enter a valid Tenure in months.");
return;
}
if (isNaN(wht) || wht < 0) {
wht = 0; // Default to 0 if invalid
}
// 3. Calculation Logic (Simple Interest basis as per standard SL FD norms for <1yr or simple annual)
// Formula: Interest = Principal * (Rate/100) * (Months/12)
var grossInterest = amount * (rate / 100) * (months / 12);
// Calculate Tax Deduction
var taxAmount = grossInterest * (wht / 100);
// Calculate Net Interest
var netInterest = grossInterest – taxAmount;
// Calculate Maturity Value (Principal + Net Interest)
var maturityValue = amount + netInterest;
// Calculate Monthly Income (if applicable)
var monthlyIncome = netInterest / months;
// 4. Formatting Function for LKR
var formatLKR = function(num) {
return "Rs. " + num.toLocaleString('en-LK', { minimumFractionDigits: 2, maximumFractionDigits: 2 });
};
// 5. Display Results
document.getElementById('grossInterestDisplay').innerText = formatLKR(grossInterest);
document.getElementById('taxDeductionDisplay').innerText = "- " + formatLKR(taxAmount);
document.getElementById('netInterestDisplay').innerText = formatLKR(netInterest);
document.getElementById('maturityValueDisplay').innerText = formatLKR(maturityValue);
// Handle Monthly Payout Display
var monthlyRow = document.getElementById('monthlyRow');
if (payoutType === 'monthly') {
monthlyRow.style.display = 'flex';
document.getElementById('monthlyIncomeDisplay').innerText = formatLKR(monthlyIncome);
// If paying monthly, maturity value is usually just the principal returned,
// but the "Total Value" conceptually includes the interest already taken.
// However, to be precise for "At Maturity", the bank gives you Principal.
// For the sake of this calculator showing "Total Returns", we keep maturityValue as total gain.
} else {
monthlyRow.style.display = 'none';
}
document.getElementById('fdResult').style.display = 'block';
}
Fixed Deposit Rates in Sri Lanka: Maximizing Your LKR Returns
Fixed Deposits (FDs) remain one of the most popular investment vehicles in Sri Lanka due to their safety and guaranteed returns. Whether you are banking with state giants like BOC and People's Bank, or private sector leaders like Commercial Bank, HNB, or Sampath Bank, understanding how your interest is calculated is crucial for financial planning. This calculator helps you estimate your returns based on current interest rates and tax regulations.
Note on Volatility: Sri Lankan FD rates are heavily influenced by the Central Bank of Sri Lanka (CBSL) policy rates. Rates have fluctuated significantly in recent years. Always confirm the specific rate with your bank branch before depositing.
How Fixed Deposit Interest is Calculated in Sri Lanka
Most Sri Lankan banks use a simple interest calculation formula for FDs with a tenure of one year or less. For longer tenures, interest may be compounded annually, though monthly payout options are also available.
In Sri Lanka, interest income from Fixed Deposits is subject to Withholding Tax (WHT). The government adjusts this rate periodically based on fiscal policy. Currently, it is common to see a 5% WHT applied to interest earnings, deducted at the source by the bank. If you are a senior citizen, you may be eligible for different tax brackets or higher interest rates.
Types of Fixed Deposits in Sri Lanka
When using the calculator, consider which type of product you are choosing:
Maturity FD: Interest is paid only when the term ends. This usually offers a slightly higher Effective Annual Rate (EAR) because the interest remains in the account for the full duration.
Monthly Interest FD: Interest is credited to your savings account every month. This is ideal for retirees or those seeking a steady passive income stream in LKR.
Senior Citizen FDs: These special accounts often offer an additional percentage (e.g., +1% or +2%) over standard rates.
Factors Affecting Your Returns
Deposit Amount: Larger deposits often attract higher tier rates.
Tenure: Contrary to popular belief, longer isn't always better. In a volatile economy like Sri Lanka, sometimes 12-month rates are higher than 5-year rates due to inflation expectations.
Bank Stability: While finance companies may offer higher rates than licensed commercial banks, they carry higher risk. Ensure the institution is regulated by the CBSL.
Frequently Asked Questions
What is the current WHT rate in Sri Lanka?
Tax rates change with government budgets. As of standard recent regulations, a 5% WHT is often applicable, but you should verify this with the Inland Revenue Department or your bank officer.
Can I withdraw my FD before maturity?
Yes, but it comes with a penalty. Sri Lankan banks typically reduce the interest rate to the savings account rate or charge a premature withdrawal fee if you break the deposit before the agreed tenure.
Which bank has the highest FD rates?
Rates change weekly. Non-bank financial institutions (NBFIs) usually offer higher rates than commercial banks, but they carry higher risk. It is advisable to compare rates from multiple sources like NSB, Seylan, and NTB before investing.