Simple Interest Calculator

Calculate the interest on a loan or investment using the simple interest formula.

Enter Details
Results
Total Amount
$0.00
Total Interest
+$0.00

How it Works

Simple interest is a quick method of calculating the interest charge on a loan or the interest income on an investment. It is determined by multiplying the daily interest rate by the principal by the number of days that elapse between payments.

This calculator assumes interest is calculated annually.

Formula

Total Interest (I) = P × r × t

Total Amount (A) = P + I

Where:
P = Principal Amount
r = Annual Interest Rate (decimal)
t = Time in Years

Example

Principal: $1,000
Rate: 5%
Time: 3 Years

  • Interest: $1,000 × 0.05 × 3 = $150.00
  • Total Amount: $1,000 + $150 = $1,150.00

Frequently Asked Questions

What is simple interest?

Simple interest is interest calculated only on the initial principal. It does not account for compounding interest (interest on interest).

How is this different from compound interest?

Compound interest calculates interest on both the principal and the accumulated interest from previous periods, leading to faster growth or debt accumulation. Simple interest remains constant based on the principal.