Compound Interest Calculator

Future value is calculated by applying a growth rate to a present sum over a specified number of periods using the formula FV = PV × (1 + r)^n. This formula accounts for compound interest, where earnings in each period are added to the principal and earn returns in subsequent periods. For investments with regular contributions, the future value of an annuity formula is added to account for each periodic deposit growing at the specified rate. Understanding this calculation helps you set clear financial goals by projecting exactly how much your savings and investments will be worth at a target date in the future.

Compound interest has been called the eighth wonder of the world because of its ability to accelerate wealth creation exponentially over time. The key to compounding is that you earn returns not only on your original investment but also on all previously accumulated interest. A $10,000 investment earning 8% annually grows to $21,589 in 10 years, $46,610 in 20 years, and $100,627 in 30 years — the growth accelerates dramatically in later years. This is why starting to invest early, even with small amounts, can produce significantly larger results than investing larger sums later in life.

Adding regular monthly contributions to your investment dramatically increases the final value compared to a one-time lump sum investment alone. For example, a $10,000 initial investment at 8% annual return grows to about $46,610 over 20 years, but adding just $200 per month to that same investment brings the total to approximately $164,000. The power of consistent contributions comes from dollar-cost averaging and the compounding effect on each successive deposit. Even modest monthly amounts — $100, $200, or $500 — can build substantial wealth over decades, making automated contributions one of the most effective wealth-building habits you can develop.

Setting realistic return expectations is crucial for meaningful financial planning and avoiding disappointment. The U.S. stock market has historically returned approximately 10% annually before inflation and about 7% after inflation, as measured by the S&P 500 over the past century. Bond returns have averaged 5% to 6% before inflation, while savings accounts and CDs currently offer 4% to 5% but have historically averaged much less. A diversified portfolio of stocks and bonds might reasonably target 6% to 8% annual returns after inflation, and using conservative estimates in your planning provides a built-in safety margin for achieving your financial goals.