Watch your money grow with the power of compounding
Future Value
Total contributions: $130,000
| Year | Contributions | Interest Earned | Ending Balance |
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Albert Einstein reportedly called compound interest the "eighth wonder of the world," and for good reason. It is the most powerful tool in any investor's arsenal, allowing your money to generate its own earnings. This free compound interest calculator lets you visualize the exponential growth of your wealth, whether you're saving for retirement, a child's education, or financial independence.
To appreciate compounding, you must first understand simple interest. **Simple interest** is calculated only on the initial amount you invest. If you invest $1,000 at 5% simple interest, you earn $50 every year—forever.
**Compound interest**, however, is calculated on the initial principal AND the accumulated interest from previous periods. In year two, you earn 5% on $1,050 ($52.50). Over decades, this "interest on interest" snowball effect creates a massive gap between those who save early and those who wait.
The most important variable in the compound interest formula isn't the interest rate or the initial investment—it's **time**. Every year you delay starting can cost you tens of thousands of dollars in future wealth. This is often called the "Cost of Delay."
Use the "Time Period" selector above to see how staying invested for 30 years vs 20 years can nearly triple your final balance, even if you never increase your monthly contribution.
The frequency with which interest is "added" to your balance matters. The more frequently interest is compounded (daily vs. monthly vs. annually), the faster your money grows. Most high-yield savings accounts compound monthly or daily, while many bonds compound semi-annually. Our tool allows you to toggle between frequencies to see the impact on your bottom line.
Want to know how long it takes for your money to double? Divide 72 by your interest rate. At a 7% return, your money doubles roughly every 10 years!
Does this account for inflation?
This calculator shows nominal growth. To see your "real" purchasing power, you should subtract the estimated inflation rate (historically ~2-3%) from your expected interest rate before calculating.
Where can I get these interest rates?
The stock market (S&P 500) has historically averaged around 7-10% annually before inflation. High-yield savings accounts and CDs currently offer 4-5%, while government bonds vary based on economic conditions.