Use the Compounded interest = P (1 + r/n) (n*t) – P
A = The future value of the investment, including the compounded interest
P = The principal (initial) investment
r = The interest rate
n = The compounding frequency (ex. monthly = 12)
t = The number of years the money is invested
The Compound Interest Formula will return the future value of the investment, which is simply the sum of the principal and the compounded interest.