Compound interest is often called the eighth wonder of the world — it is the process by which interest earns interest, causing your savings or investments to grow exponentially over time. Our compound interest calculator shows you exactly how much your money will grow based on your initial deposit, regular contributions, interest rate, and investment period. The longer you invest, the more dramatic the compounding effect becomes. This calculator supports both annual and monthly compounding, and you can add regular monthly contributions to see how consistent saving accelerates growth.