Note: Amana Bank operates on Islamic banking principles (Mudaraba). Rates shown are anticipated/historical rates and are subject to the bank's actual business performance. WHT is subject to government regulations.
function calculateAmanaProfit() {
// 1. Get Inputs
var amountInput = document.getElementById('depositAmount');
var tenureInput = document.getElementById('tenure');
var rateInput = document.getElementById('profitRate');
var payoutInput = document.getElementById('profitDistribution');
var whtInput = document.getElementById('wht');
var principal = parseFloat(amountInput.value);
var months = parseInt(tenureInput.value);
var ratePercent = parseFloat(rateInput.value);
var whtPercent = parseFloat(whtInput.value);
var payoutType = payoutInput.value;
// 2. Validate
if (isNaN(principal) || principal <= 0) {
alert("Please enter a valid investment amount.");
return;
}
if (isNaN(ratePercent) || ratePercent < 0) {
alert("Please enter a valid anticipated profit rate.");
return;
}
// 3. Calculation Logic
// Formula: Profit = Principal * (Rate/100) * (Months/12)
var grossProfit = principal * (ratePercent / 100) * (months / 12);
// Calculate Tax
var taxAmount = grossProfit * (whtPercent / 100);
// Net Profit
var netProfit = grossProfit – taxAmount;
// Maturity Value (Principal + Net Profit)
var maturityValue = principal + netProfit;
// Monthly Payout (if applicable)
var monthlyPayout = 0;
if (payoutType === 'monthly') {
monthlyPayout = netProfit / months;
}
// 4. Update UI
// Helper for formatting currency (LKR)
var formatter = new Intl.NumberFormat('en-LK', {
style: 'currency',
currency: 'LKR',
minimumFractionDigits: 2
});
document.getElementById('res_amount').innerHTML = formatter.format(principal);
document.getElementById('res_tenure').innerHTML = months + " Months";
document.getElementById('res_rate').innerHTML = ratePercent + "%";
document.getElementById('res_gross').innerHTML = formatter.format(grossProfit);
document.getElementById('res_tax').innerHTML = "-" + formatter.format(taxAmount);
document.getElementById('res_net').innerHTML = formatter.format(netProfit);
document.getElementById('res_total').innerHTML = formatter.format(maturityValue);
// Handle Monthly vs Maturity display
var monthlyRow = document.getElementById('monthly_row');
var maturityRow = document.getElementById('maturity_row');
if (payoutType === 'monthly') {
monthlyRow.style.display = 'flex';
document.getElementById('res_monthly').innerHTML = formatter.format(monthlyPayout);
// If taking monthly profits, maturity value usually is just the principal returned at the end,
// but the calculator shows total accumulation. We will clarify the label logic.
// For Amana, "Maturity Value" in a monthly context usually means Principal, as profit is already taken.
// But to keep simple math logic: Total Value = Principal + Total Net Profit.
// We will hide Total Maturity Value row if monthly to avoid confusion, or rename it.
// Let's show "Principal Returned" instead if monthly.
document.getElementById('res_total').innerHTML = formatter.format(principal);
maturityRow.querySelector('.result-label').innerText = "Principal Returned at End:";
} else {
monthlyRow.style.display = 'none';
maturityRow.querySelector('.result-label').innerText = "Total Value at Maturity:";
document.getElementById('res_total').innerHTML = formatter.format(maturityValue);
}
document.getElementById('results').style.display = 'block';
}
Understanding Amana Bank's Profit Sharing Model
Unlike conventional banks that offer fixed interest rates, Amana Bank operates on the principles of Islamic Banking. The Fixed Deposit product is based on the concept of Mudaraba. In this partnership, you act as the capital provider (Rabb-ul-Maal) and the bank acts as the investment manager (Mudarib).
Instead of a guaranteed interest rate, you share in the profits generated by the bank's investment portfolio. The "Anticipated Profit Rate" used in this calculator is based on historical performance and the Profit Sharing Ratio (PSR) agreed upon at the time of deposit.
Key Difference: Profit vs. Interest
Conventional FD: The bank borrows money from you and pays interest (Riba), regardless of whether they make a profit or loss. Amana Bank FD: The bank invests your funds in Sharia-compliant businesses. Profits earned are shared between you and the bank. Losses, if any (unless caused by negligence), are borne by the investor.
How to Use This Calculator
Since Amana Bank rates are variable based on monthly performance, this tool helps you estimate potential returns based on current published anticipated rates.
Investment Amount: Enter the value in LKR. Amana Bank typically requires a minimum deposit (e.g., LKR 5,000) to open a Term Investment Account.
Tenure: Select how long you wish to invest. Longer tenures usually attract a higher Profit Sharing Ratio (PSR).
Anticipated Profit Rate: Enter the annualized rate you see on the bank's latest rate sheet. This is not a guarantee but an indication of recent payouts.
Profit Payout: Choose "Monthly" if you want income every month, or "At Maturity" to reinvest the profit for the full term. Note that monthly payouts might have a slightly different effective yield.
WHT (Withholding Tax): In Sri Lanka, a Withholding Tax (often 5%) may apply to interest/profit income exceeding certain thresholds. Select 5% to see your net "take-home" profit.
Factors Affecting Your Return
Your final return at Amana Bank depends on three main factors:
The Profit Sharing Ratio (PSR): This is the pre-agreed percentage of profit split between you and the bank (e.g., 60:40).
Bank Performance: The actual gross income the bank generates from its investment pool during your tenure.
Tenure Selection: 1-year to 5-year deposits generally carry higher weightages in the profit pool compared to 1-month or 3-month deposits.
Current Tax Regulations (Sri Lanka)
As of recent tax updates in Sri Lanka, Fixed Deposit income is subject to Withholding Tax (WHT) or Advanced Income Tax (AIT). While the calculator allows you to toggle 5%, always check with the bank or a tax consultant for the most current statutory deductions applicable to your specific tax profile.