Compound Interest Calculator

Visualize the "eighth wonder of the world" and forecast your long-term wealth growth.

Starting Balance: $0.00
Total Contributions: $0.00
Interest Earned: $0.00
$0.00
Rule of 72: At this rate, your money will double every 9 years.

What is Compound Interest?

Compound interest is the interest calculated on the initial principal and also on the accumulated interest of previous periods. Think of it as "interest on interest." Over long periods, this creates exponential growth that can turn modest savings into a significant nest egg.

The Compound Interest Formula

Our calculator uses the standard formula for future value with periodic contributions:

A = P(1 + r/n)^(nt) + PMT × {[(1 + r/n)^(nt) - 1] / (r/n)}

Why Compounding Frequency Matters

The more frequently interest is compounded (daily vs. annually), the faster your wealth grows. Daily compounding is technically the most efficient for the investor, as your earned interest begins generating its own return almost immediately.

The Rule of 72

The **Rule of 72** is a quick financial shortcut to estimate how many years it will take for an investment to double at a fixed annual interest rate. By dividing 72 by your annual rate of return, you can quickly see the impact of time on your wealth.