Simple Interest Calculator
This calculator helps you quickly determine the simple interest earned on an investment or the simple interest paid on a loan. Simple interest is calculated only on the principal amount, meaning it does not compound. It's a straightforward way to understand the basic cost of borrowing or the basic return on investment.
Understanding Simple Interest
Simple interest is a method of calculating the interest charge on a loan or the interest earned on an investment. It is determined by multiplying the daily interest rate by the principal by the number of days that elapse between payments.
The formula for simple interest is:
Simple Interest (SI) = (P × R × T) / 100
- P = Principal Amount (the initial amount of money)
- R = Annual Interest Rate (expressed as a percentage)
- T = Time Period (in years)
The total amount (A) to be repaid or received after the time period is calculated as:
Total Amount (A) = Principal (P) + Simple Interest (SI)
Example: If you invest $5,000 (Principal) at an annual interest rate of 4% (Rate) for 5 years (Time), the simple interest earned would be:
SI = (5000 × 4 × 5) / 100 = $1,000
The total amount after 5 years would be $5,000 + $1,000 = $6,000.
function calculateSimpleInterest() {
var principalInput = document.getElementById("principal");
var rateInput = document.getElementById("rate");
var timeInput = document.getElementById("time");
var resultDiv = document.getElementById("result");
var principal = parseFloat(principalInput.value);
var rate = parseFloat(rateInput.value);
var time = parseFloat(timeInput.value);
if (isNaN(principal) || isNaN(rate) || isNaN(time) || principal < 0 || rate < 0 || time < 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
var simpleInterest = (principal * rate * time) / 100;
var totalAmount = principal + simpleInterest;
resultDiv.innerHTML = "
Calculation Results
" +
"Principal Amount: $" + principal.toFixed(2) + "" +
"Annual Interest Rate: " + rate.toFixed(2) + "%" +
"Time Period: " + time.toFixed(2) + " Years" +
"
Simple Interest Earned/Paid: $" + simpleInterest.toFixed(2) + "" +
"
Total Amount (Principal + Interest): $" + totalAmount.toFixed(2) + "";
}
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