Unlock the power of exponential growth. Calculate compound interest with basic or contribution modes, flexible currency settings, and a detailed period-by-period breakdown.
Each period applies compound interest once. A period can represent a month, quarter, year, or any timeframe.
Final Amount
Total Interest
$6,288.95
Total Return
62.9%
| Period | Interest | Total | Return |
|---|---|---|---|
| 1 | $500.00 | $10,500.00 | 5.0% |
| 2 | $525.00 | $11,025.00 | 10.3% |
| 3 | $551.25 | $11,576.25 | 15.8% |
| 4 | $578.81 | $12,155.06 | 21.6% |
| 5 | $607.75 | $12,762.82 | 27.6% |
| 6 | $638.14 | $13,400.96 | 34.0% |
| 7 | $670.05 | $14,071.00 | 40.7% |
| 8 | $703.55 | $14,774.55 | 47.7% |
| 9 | $738.73 | $15,513.28 | 55.1% |
| 10 | $775.66 | $16,288.95 | 62.9% |
Compound interest is the result of reinvesting interest, rather than paying it out, so that interest in the next period is then earned on the principal sum plus previously accumulated interest. This creates a geometric progression of growth that accelerates over time. Albert Einstein is often attributed with calling it the “eighth wonder of the world,” and whether or not he actually said it, the mathematics behind it are undeniably powerful.
Basic mode calculates growth from a single lump-sum investment — you deposit once and let it grow. This is ideal for modeling inheritance, lottery winnings, or a one-time bonus. Contribution mode adds a fixed amount each period, simulating regular savings plans like retirement contributions or monthly investment deposits. The combination of compounding and regular contributions creates a dramatically steeper growth curve than either strategy alone.
Where F is the final amount, P is the principal, r is the interest rate per period, and nis the number of compounding periods. A “period” is flexible — it can represent a month, a quarter, or a year, depending on how your interest compounds. What matters is the number of times your money compounds, not the label you give each period.
A quick mental shortcut: divide 72 by your interest rate per period to estimate how many periods it takes for your money to double. At 6% per period, your investment roughly doubles every 12 periods. At 8%, every 9 periods. At 12%, every 6 periods. This simple rule gives you an intuitive feel for the power of different rates without reaching for a calculator.
A period is a single compounding cycle. If your bank compounds monthly, one period = one month. If it compounds yearly, one period = one year. Enter the rate that corresponds to your period — for example, if you have a 12% annual rate that compounds monthly, enter 1% as the rate and 12 as the number of periods for one year of growth.
Use Contribution mode when you plan to add money regularly — for example, monthly savings into an index fund, quarterly retirement contributions, or annual deposits. The calculator adds the contribution at the end of each period before the next compounding cycle.
This calculator provides a mathematical projection based on a fixed interest rate. Real-world investments have variable returns, fees, taxes, and inflation. Use this tool for educational purposes and rough planning — consult a financial advisor for investment decisions.