Compound Interest Calculator

Albert Einstein supposedly called compound interest the "eighth wonder of the world." It is the most powerful force in personal finance, allowing you to build significant wealth through consistent investment and patience over time. ### The Magic of "Interest on Interest" Unlike simple interest, which is only calculated on the principal, compound interest adds the interest earned in one period back into the principal for the next period. This creates a "snowball effect" where your balance grows at an accelerating rate as time goes on. ### Key Variables of Compounding - **Time Duration:** This is the most critical factor. The longer you leave your money invested, the more "rounds" of compounding occur. Starting even a few years earlier can result in hundreds of thousands of dollars in difference by retirement. - **Interest Rate:** Your rate of return determines how fast your money grows. A difference of just 1-2% over 30 years can lead to a massive gap in your final balance. - **Compounding Frequency:** The more often interest is added back to the principal (e.g., daily vs. annually), the faster the wealth grows. ### The Rule of 72 To quickly estimate how long it takes for your investment to double, use the "Rule of 72." Divide 72 by your expected annual rate of return. For example, at a 10% return, your money will double roughly every 7.2 years. Use this calculator to experiment with different frequencies and rates to see visually how your money can work for you in the long run!