FV = P * (1 + (R / N))N * T
FV = P + I
where:
FV = Future value
I = Interest amount
P = Principal initial amount
R = Nominal interest rate per year (as a decimal, not in percentage)
T = Time period in years
N = Number of compounding periods in one year
Other variations of the compound interest equation are used to calculate:
- The future value (FV) and interest amount (I)
FV = P * (1 + (R / N))N * T
I = FV - P
- The principal amount (P)
P = FV or P = I (1 + (R / N))N * T (1 + (R / N))N * T - 1 
- The nominal interest rate per year (as a decimal, not in percentage)
R = N * ((FV / P)1 / (N * T) - 1)
or
R = N * ((I / P) + 1)1 / (N * T) - 1)
- The time period (T) in years
T = log(FV / P) or T = log((I / P) + 1) N * log(1 + (R / N)) N * log(1 + (R / N))
- The compounding periods (N) in one year
N = log(FV / P) or N = log((I / P) + 1) T * log(1 + R) T * log(1 + R)
- The effective interest rate (Re) (as a decimal, not in percentage)
Re = (1 + (R / N))N - 1
Note:
The effective interest rate is the equivalent rate of compound interest earned over a period of one year for a nominal interest rate per year which is compounded twice or more over the year.