Compound interest

Compound interest is interest charged also on interest already added — "interest on interest". The balance after $n$ periods:

$K_n=K_0\left(1+\frac{p}{100\,m}\right)^{m\,n}$

where $K_0$ is the initial principal, $p$ — the annual interest rate, $m$ — the number of compounding periods per year (annual $m=1$, quarterly $m=4$, monthly $m=12$), and $n$ — the number of years.

The calculator shows the final balance, total interest, the effective annual rate and a growth chart — and compares the result with simple interest, so you can see the power of compounding.