Enter a starting principal, interest rate, compounding frequency, and time period — plus an optional monthly contribution — to calculate the future value and total interest earned.
How to Use the Compound Interest Calculator
Principal, rate, compounding frequency, and years are required; the monthly contribution field is optional — leave it at zero to see growth on the lump sum alone.
Interest earning interest is the entire idea behind compounding, and the effect compounds faster the more often it's calculated — daily beats monthly, monthly beats annually, for the same stated rate.
FV = P(1 + r/n)ⁿᵗP is the starting principal, r the annual rate, n the compounding frequency per year, t the time in years. Add a monthly contribution and this tool layers a second calculation on top — each deposit compounds from the moment it's made, so contributions made early in the timeline end up worth more at the end than ones made later, even though every deposit is the same size.
The "Interest Earned" figure in the result is the account's total growth minus every dollar you put in yourself — the part the money made on its own.