Compound interest (or compounding interest) is the interest on a loan or deposit calculated based on both the initial principal and the accumulated interest from previous periods is calculated using Future Value of Investment = Principal Investment Amount*(1+(Annual Interest Rate/Number of Periods))^(Number of Periods*Number of Years Money is Invested). To calculate Compound Interest, you need Principal Investment Amount (A), Annual Interest Rate (i), Number of Periods (n) & Number of Years Money is Invested (T). With our tool, you need to enter the respective value for Principal Investment Amount, Annual Interest Rate, Number of Periods & Number of Years Money is Invested and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.